user-mode-linux-user

Re: [uml-user] Kernel panic - not syncing: No init found using initramfs

[Vegard N. <veg...@gm...>]

On 16 May 2016 at 10:05, kail-gj <an_...@12...> wrote:
> Hi,
>     I build my uml from source with CONFIG_INITRAMFS_SOURCE configured with
> a rootfs text file.  I specify the init file to  busybox as
>     file /bin/busybox /home/xxxx/busybox/busybox 755 0 0 /init /bin/sh in
> rootfs text file.
>     But it does not work and output "kernel panic - not syncing: No init
> found" error. The full boot log is followed.
>     Please help me, thanks.
> -------------------------------------------------
> boot log:

You still need to pass init= on the command line, no? This shows you
didn't pass anything:

> Kernel command line: root=98:0
[...]
> Kernel panic - not syncing: No init found.  Try passing init= option to
> kernel.


Vegard

[uml-user] [PATCH 0263/1529] Fix typo

[Andrea G. <and...@ge...>]

Signed-off-by: Andrea Gelmini <and...@ge...>
---
 arch/um/os-Linux/time.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c
index 0e39b99..6caa556 100644
--- a/arch/um/os-Linux/time.c
+++ b/arch/um/os-Linux/time.c
@@ -91,7 +91,7 @@ int os_timer_set_interval(void* timer, void* i)
 /**
  * os_timer_remain() - returns the remaining nano seconds of the given interval
  *                     timer
- * Because this is the remaining time of an interval timer, which correspondends
+ * Because this is the remaining time of an interval timer, which correspondences
  * to HZ, this value can never be bigger than one second. Just
  * the nanosecond part of the timer is returned.
  * The returned time is relative to the start time of the interval timer.
-- 
2.8.2.534.g1f66975

[uml-user] Kernel panic - not syncing: No init found using initramfs

[kail-gj <an_...@12...>]

Hi, 
    I build my uml from source with CONFIG_INITRAMFS_SOURCE configured with a rootfs text file.  I specify the init file to  busybox as
    file /bin/busybox /home/xxxx/busybox/busybox 755 0 0 /init /bin/sh in rootfs text file. 
    But it does not work and output "kernel panic - not syncing: No init found" error. The full boot log is followed. 
    Please help me, thanks.
-------------------------------------------------
boot log:
-------------------------------------------------
$ ./linux 
Core dump limits :
soft - 0
hard - NONE
Checking that ptrace can change system call numbers...OK
Checking syscall emulation patch for ptrace...OK
Checking advanced syscall emulation patch for ptrace...OK
Checking for tmpfs mount on /dev/shm...OK
Checking PROT_EXEC mmap in /dev/shm/...OK
Checking for the skas3 patch in the host:
  - /proc/mm...not found: No such file or directory
  - PTRACE_FAULTINFO...not found
  - PTRACE_LDT...not found
UML running in SKAS0 mode
Linux version 2.6.32.8 (chipX /home/chipX/chipX/fhos/trunk/build.um.d/linux@suzhou-chipX) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-3) (GCC) ) #1 Sun May 15 17:42:40 CST 2016
Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 8080
Kernel command line: root=98:0
PID hash table entries: 128 (order: -2, 1024 bytes)
Dentry cache hash table entries: 4096 (order: 3, 32768 bytes)
Inode-cache hash table entries: 2048 (order: 2, 16384 bytes)
Memory: 28892k available
Hierarchical RCU implementation.
NR_IRQS:15
Calibrating delay loop... 91.54 BogoMIPS (lpj=457728)
Mount-cache hash table entries: 256
Checking that host ptys support output SIGIO...Yes
Checking that host ptys support SIGIO on close...No, enabling workaround
Using 2.6 host AIO
NET: Registered protocol family 16
Switching to clocksource itimer
NET: Registered protocol family 2
IP route cache hash table entries: 512 (order: 0, 4096 bytes)
TCP established hash table entries: 1024 (order: 2, 16384 bytes)
TCP bind hash table entries: 1024 (order: 1, 8192 bytes)
TCP: Hash tables configured (established 1024 bind 1024)
TCP reno registered
NET: Registered protocol family 1
NET: Registered protocol family 22
TCP cubic registered
NET: Registered protocol family 17
Initialized stdio console driver
Console initialized on /dev/tty0
console [tty0] enabled
IRQ 3/console-write: IRQF_DISABLED is not guaranteed on shared IRQs
IRQ 2/console: IRQF_DISABLED is not guaranteed on shared IRQs
IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
Kernel panic - not syncing: No init found.  Try passing init= option to kernel.


Modules linked in:
Pid: 1, comm: swapper Not tainted 2.6.32.8
RIP: 0033:[<0000003630a32907>]
RSP: 00007ffff3b091b8  EFLAGS: 00000206
RAX: 0000000000000000 RBX: 00000000000063fc RCX: ffffffffffffffff
RDX: 0000000000000000 RSI: 0000000000000013 RDI: 00000000000063fc
RBP: 00000000000063f8 R08: 0000000000000000 R09: 00007ffff3b0920c
R10: 00007ffff3b08f40 R11: 0000000000000206 R12: 00007f56d0bce6a8
R13: 00007ffff3b093b8 R14: 0000000000000008 R15: 0000000000000001
Call Trace: 
61c27dd8:  [<600115ef>]
61c27df8:  [<600368c2>]
61c27e38:  [<600ef777>]
61c27e58:  [<60060b3d>]
61c27ed8:  [<6000e31a>]
61c27ef8:  [<6000fea9>]
61c27f28:  [<6000e0a9>]
61c27f48:  [<6000117e>]
61c27f68:  [<600188fe>]
61c27f70:  [<600010ac>]
61c27fb8:  [<600188e3>]
61c27fd8:  [<6000f3f3>]


Segmentation fault (core dumped)

[uml-user] Device eth0 does not seem to be present

[kail-gj <an_...@12...>]

Hi,


    My uml came to a strange status, which open up 6 xterm windows and hang on.
    Two questions:
    1. Why does it to bring up eth0?
    2. Why 6 xterm windows is opened?
    3. Why my uml is hanged on?
    
    Any device is appreciated.


Jotus
    ---------------------------------------------------------
    boot log:
    --------------------------------------------------------
    Bringing up loopback interface:    [OK]
    Bringing up interface  eth0: Device eth0 does not seem to be present, delaying initialization. [FAILED]
    FATAL: Could not load /lib/modules/2.6.32.8/modules.dep: No such file or directory
    Mount other filesystem:    [OK]
    Retrigger failed udev events[OK]
    IRQ 13/xterm: IRQ_DISABLED is not guaranteed on shared IRQs
    Warning: Cannot convert string "nil2" to type FontStruct
    IRQ 13/xterm: IRQ_DISABLED is not guaranteed on shared IRQs
    Warning: Cannot convert string "nil2" to type FontStruct
    IRQ 13/xterm: IRQ_DISABLED is not guaranteed on shared IRQs
    Warning: Cannot convert string "nil2" to type FontStruct
    IRQ 13/xterm: IRQ_DISABLED is not guaranteed on shared IRQs
    Warning: Cannot convert string "nil2" to type FontStruct
    IRQ 13/xterm: IRQ_DISABLED is not guaranteed on shared IRQs
    Warning: Cannot convert string "nil2" to type FontStruct
    IRQ 13/xterm: IRQ_DISABLED is not guaranteed on shared IRQs
    Warning: Cannot convert string "nil2" to type FontStruct
    remove_umid_dir - remove_files_and_dir failed with err = -3

Re: [uml-user] mount: cannot remount block device /dev/ubda read-write, is write-protected

[kail-gj <an_...@12...>]

Hi,
    I change the root_fs i/o mode to 777 to solve the problem. Thanks.


    >I build my UML linux from source and build my filesystem using mkrootfs tools, and run with ./linux ubda=../../rfs-1/root_fs mem=512m.
    >I changed my mkrootfs one line from 
   >         addline etc/fstab               "/dev/ubd/0      /               ext2    defaults 1 1"
   >to
   >        addline etc/fstab               "/dev/ubda      /               ext2    defaults 0 0"
   > to solve the other problem "[/sbin/fsck.ext2 (1) -- /] fsck.ext2 -a /dev/ubd/0".
    >Now a new problem troubles me. The boot log is with "

[uml-user] mount: cannot remount block device /dev/ubda read-write, is write-protected

[kail-gj <an_...@12...>]

Hi, 
    I build my UML linux from source and build my filesystem using mkrootfs tools, and run with ./linux ubda=../../rfs-1/root_fs mem=512m.
    I changed my mkrootfs one line from 
            addline etc/fstab               "/dev/ubd/0      /               ext2    defaults 1 1"
    to
            addline etc/fstab               "/dev/ubda      /               ext2    defaults 0 0"
    to solve the other problem "[/sbin/fsck.ext2 (1) -- /] fsck.ext2 -a /dev/ubd/0".
    Now a new problem troubles me. The boot log is with "
RQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
Welcome to Red Hat Enterprise Linux Server
Starting udev: modprobe: FATAL: Could not load /lib/modules/2.6.32.8/modules.dep: No such file or directory


line_ioctl: tty0: unknown ioctl: 0x541e
[  OK  ]
Setting hostname localhost:  [  OK  ]
Checking filesystems
Checking all file systems.
[  OK  ]
Remounting root filesystem in read-write mode:  mount: cannot remount block device /dev/ubda read-write, is write-protected
[FAILED]
can't create lock file /etc/mtab~408: Read-only file system (use -n flag to override)
Mounting local filesystems:  [FAILED]
touch: cannot touch `/.autorelabel': Read-only file system
touch: cannot touch `/var/lib/random-seed': Read-only file system
chmod: cannot access `/var/lib/random-seed': No such file or directory
rm: cannot remove `/var/run/utmp': Read-only file system
/etc/rc.d/rc.sysinit: line 597: /var/run/utmp: Read-only file system
touch: cannot touch `/var/log/wtmp': Read-only file system
/etc/rc.d/rc.sysinit: line 594: plymouth: command not found
chgrp: changing group of `/var/run/utmp': Read-only file system
chgrp: changing group of `/var/log/wtmp': Read-only file system
chmod: changing permissions of `/var/run/utmp': Read-only file system
chmod: changing permissions of `/var/log/wtmp': Read-only file system
chown: cannot access `/tmp/.ICE-unix': No such file or directory
Enabling /etc/fstab swaps:  [  OK  ]
modprobe: FATAL: Could not load /lib/modules/2.6.32.8/modules.dep: No such file or directory


/etc/rc.d/rc.sysinit: line 654: /var/log/dmesg: Read-only file system
/etc/rc.d/rc.sysinit: line 659: plymouth: command not found
IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
modprobe: FATAL: Could not load /lib/modules/2.6.32.8/modules.dep: No such file or directory


IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
Entering non-interactive startup
FATAL: Could not load /lib/modules/2.6.32.8/modules.dep: No such file or directory
Bringing up loopback interface:  [  OK  ]
Bringing up interface eth0:  Device eth0 does not seem to be present, delaying initialization.
[FAILED]
FATAL: Could not load /lib/modules/2.6.32.8/modules.dep: No such file or directory
touch: cannot touch `/var/lock/subsys/network': Read-only file system
awk: cmd. line:1: fatal: cannot open file `/etc/mtab' for reading (No such file or directory)
xterm_open : run_helper failed, errno = 2
Failed to open console 2, err = -2
xterm_open : run_helper failed, errno = 2
Failed to open console 3, err = -2
xterm_open : run_helper failed, errno = 2
Failed to open console 5, err = -2
xterm_open : run_helper failed, errno = 2
Failed to open console 1, err = -2
xterm_open : run_helper failed, errno = 2
Failed to open console 6, err = -2
xterm_open : run_helper failed, errno = 2
Failed to open console 4, err = -2
IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
init: tty (/dev/tty2) main process (571) terminated with status 1
IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
init: tty (/dev/tty2) main process ended, respawning
xterm_open : run_helper failed, errno = 2
"
    Any suggestion or hints is much appreciated.


    @Toralf Forster, I find you had met the same problem and how did you solve it finally?


Jotus.


|
>From: Toralf Förster <toralf.foerster@gm...> - 2012-10-25 19:41:18
|
|
>-----BEGIN PGP SIGNED MESSAGE-----
>Hash: SHA1

>I cloned a 1.2 GB UML file w/ ext3 fs (Gentoo Linux) into a 2.0 GB bigger file with ext4. Trying to boot the >image however I always get :

>...
> [ ok ]
> * Checking local filesystems  ...
>stable: clean, 81157/122160 files, 265527/488281 blocks
> [ ok ]
> * Remounting root filesystem read/write ...
>mount: cannot remount block device /dev/ubda read-write, is write-protected
> * Root filesystem could not be mounted read/write
 



>probably PEBKAC - but what I missed ????
|




 

[uml-user] UML boot question for help

[kail-gj <an_...@12...>]

Hi,


     I try to boot my uml with command ./linux ubda=../../rfs-1/root_fs mem=512m but it is failed. The boot log is 


$ ./linux ubda=../../rfs-1/root_fs mem=512m
Core dump limits :
soft - 0
hard - NONE
Checking that ptrace can change system call numbers...OK
Checking syscall emulation patch for ptrace...OK
Checking advanced syscall emulation patch for ptrace...OK
Checking for tmpfs mount on /dev/shm...OK
Checking PROT_EXEC mmap in /dev/shm/...OK
Checking for the skas3 patch in the host:
  - /proc/mm...not found: No such file or directory
  - PTRACE_FAULTINFO...not found
  - PTRACE_LDT...not found
UML running in SKAS0 mode
Adding 16764928 bytes to physical memory to account for exec-shield gap
Linux version 2.6.32.8 (chipX /home/chipX/chipX/fhos/trunk/linux@suzhou-chipX) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-3) (GCC) ) #1 Fri May 13 10:46:03 CST 2016
Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 133317
Kernel command line: ubda=../../rfs-1/root_fs mem=512m root=98:0
PID hash table entries: 4096 (order: 3, 32768 bytes)
Dentry cache hash table entries: 131072 (order: 8, 1048576 bytes)
Inode-cache hash table entries: 65536 (order: 7, 524288 bytes)
Memory: 504188k available
Hierarchical RCU implementation.
NR_IRQS:15
Calibrating delay loop... 100.76 BogoMIPS (lpj=503808)
Mount-cache hash table entries: 256
Checking that host ptys support output SIGIO...Yes
Checking that host ptys support SIGIO on close...No, enabling workaround
Using 2.6 host AIO
NET: Registered protocol family 16
bio: create slab <bio-0> at 0
Switching to clocksource itimer
NET: Registered protocol family 2
IP route cache hash table entries: 8192 (order: 4, 65536 bytes)
TCP established hash table entries: 32768 (order: 7, 524288 bytes)
TCP bind hash table entries: 32768 (order: 6, 262144 bytes)
TCP: Hash tables configured (established 32768 bind 32768)
TCP reno registered
NET: Registered protocol family 1
IRQ 9/mconsole: IRQF_DISABLED is not guaranteed on shared IRQs
mconsole (version 2) initialized on /home/chipX/.uml/mq9xu4/mconsole
Checking host MADV_REMOVE support...OK
VFS: Disk quotas dquot_6.5.2
Dquot-cache hash table entries: 512 (order 0, 4096 bytes)
msgmni has been set to 985
io scheduler noop registered
io scheduler anticipatory registered (default)
io scheduler deadline registered
io scheduler cfq registered
TCP cubic registered
NET: Registered protocol family 17
Initialized stdio console driver
Console initialized on /dev/tty0
console [tty0] enabled
Initializing software serial port version 1
console [mc-1] enabled
 ubda: unknown partition table
VFS: Mounted root (ext2 filesystem) readonly on device 98:0.
IRQ 3/console-write: IRQF_DISABLED is not guaranteed on shared IRQs
IRQ 2/console: IRQF_DISABLED is not guaranteed on shared IRQs
IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
Welcome to Red Hat Enterprise Linux Server
Starting udev: modprobe: FATAL: Could not load /lib/modules/2.6.32.8/modules.dep: No such file or directory


line_ioctl: tty0: unknown ioctl: 0x541e
[  OK  ]
Setting hostname localhost:  [  OK  ]
Checking filesystems
Checking all file systems.
[/sbin/fsck.ext2 (1) -- /] fsck.ext2 -a /dev/ubd/0 #### Different from your boot log
ext2fs_check_if_mount: Can't check if filesystem is mounted due to missing mtab file while determining whether /dev/ubd/0 is mounted.
fsck.ext2: No such file or directory while trying to open /dev/ubd/0
/dev/ubd/0: 
The superblock could not be read or does not describe a correct ext2
filesystem.  If the device is valid and it really contains an ext2
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
    e2fsck -b 8193 <device>


[FAILED]


*** An error occurred during the file system check.
*** Dropping you to a shell; the system will reboot
*** when you leave the shell.
/dev/fd/9: line 2: plymouth: command not found
Press enter for maintenance
(or type Control-D to continue):


Any suggestion or hint is much appreciated.


Thanks, Jotus

Re: [uml-user] Login prompt not seen

[Michael R. <mc...@sa...>]

Ashwanth kumar <iam...@gm...> wrote:
    > I do see the hello on the main console when i run the above mentioned
    > commands from a virtual console.

Then, there is no plumbing problem.

Your /sbin/init [check /etc/inittab] (or maybe systemd: I have no idea) isn't
starting a getty instance on /dev/console.

--
]               Never tell me the odds!                 | ipv6 mesh networks [
]   Michael Richardson, Sandelman Software Works        | network architect  [
]     mc...@sa...  http://www.sandelman.ca/        |   ruby on rails    [

[uml-user] Strange behavior when trying to use UML with Yocto

[Marcelo E. M. <mar...@hp...>]

Hi,

I apologize in advance for the fuzzy details, but I'm hoping someone can 
ask the right questions to provide that missing information.

A couple of people are trying to integrate UML with a Yocto-based 
distribution called OpenSwitch (http://openswitch.net/). The relevant 
change request can be seen here:

https://review.openswitch.net/#/c/6079/

The OPS build process builds a full kernel and userspace, and Christian 
did a proof of concept integrating UML with that build process. 
Everything *seems* to be working fine, except that we are seeing strange 
behaviors at runtime.

Christian build the whole thing inside a VM, which has Debian 8 
installed. When he tries to boot the image, everything works fine.

When I try to reproduce Christian's results, I use a computer with 
Debian 8 installed in it (no VM), generate the image and boot. That 
alone seems to work, but several components inside the system exhibit 
strange behavior. OPS uses systemd, and journald starts spewing out 
messages about not being able to write a log entry. There's another 
component (OVSDB) which has a helper program create a database for it at 
boot time, and that component is behaving in a strange manner: it reads 
a file to translate it into a different format, and although strace does 
not reveal any errors, the output file is truncated (filesystem is 
ext4). There's also an issue with OpenSSH generating keys at boot time, 
and those keys are also truncated.

We have even tried with Christian's generated image on the computer 
where things fail, and it stills fails. I have generate an image out of 
a chroot to eliminate inconsistencies between the two build 
environments, and as far as we can tell, everything is the same, but it 
still fails. Christian tried building the same thing using actual 
hardware (no VM), and it fails. Weird thing is that if you take that 
image to the VM, it works.

Perhaps we are misunderstanding how UML works. Is it possible to run 
kernel version X (UML) on top of kernel version Y (X > Y)? How are 
system calls handled? I'm asking because we found a thread where someone 
asked the kernel headers to be installed so that a toolchain for the 
target environment can be generated, but the reply back then is that 
"that doesn't make sense". In our case the host is running 3.16 and the 
UML kernel is 4.5. The VM where things work is the same.

One thing we have noticed is that when the host is not a VM, systemd 
says the virtualization technology is UML. When the host is the VM, 
systemd says the virtualization technology is vmware. Scanning the code 
it does not seem to be doing anything different based on that.

I can provide the binaries that I compiled and are failing upon request 
if you want to take a look at the error yourself.

I'm looking forward to your questions regarding this,

Marcelo

Re: [uml-user] Login prompt not seen

[Ashwanth k. <iam...@gm...>]

Hi Michael,

I do see the hello on the main console when i run the above mentioned
commands from a virtual console.

Thanks,
Ashwanth

On Tue, Mar 29, 2016 at 7:11 PM, Michael Richardson <mc...@sa...> wrote:
> Do you have a getty running on /dev/console?
>
> What happens if you do:
>      sudo -s
>      echo hello >/dev/console
>
> (you should see "hello" on the console)
>
> --
> ]               Never tell me the odds!                 | ipv6 mesh networks [
> ]   Michael Richardson, Sandelman Software Works        | network architect  [
> ]     mc...@sa...  http://www.sandelman.ca/        |   ruby on rails    [
>

Re: [uml-user] Login prompt not seen

[Michael R. <mc...@sa...>]

Do you have a getty running on /dev/console?

What happens if you do:
     sudo -s
     echo hello >/dev/console

(you should see "hello" on the console)

--
]               Never tell me the odds!                 | ipv6 mesh networks [
]   Michael Richardson, Sandelman Software Works        | network architect  [
]     mc...@sa...  http://www.sandelman.ca/        |   ruby on rails    [

Re: [uml-user] Login prompt not seen

[Ashwanth k. <iam...@gm...>]

On Mon, Mar 28, 2016 at 11:38 PM, Ashwanth kumar <iam...@gm...>
wrote:
>
>
> Hi,
>
> I am trying to run UML on linux-4.4.6 with rootfs created by closely
following this link
http://web2.clarkson.edu/class/cs644/kernel/setup/uml/uml.html except for
the inittab part.
> I do not see the login prompt when i run it. But i am able to connect to
the virtual consoles using screen.
>
> Do not see output file descriptor for con0. Am i missing something in my
rootfs?
> $ uml_mconsole VoTvJ8 config con0
> OK fd:0
>
> Attaching the stdout from running below cmd
> $./linux ubd0=../rootfs mem=256M
>
>
> Thanks,
> Ashwanth

[uml-user] Login prompt not seen

[Ashwanth k. <iam...@gm...>]

Hi,

I am trying to run UML on linux-4.4.6 with rootfs created by closely
following this link
http://web2.clarkson.edu/class/cs644/kernel/setup/uml/uml.html except for
the inittab part.
I do not see the login prompt when i run it. But i am able to connect to
the virtual consoles using screen.

Do not see output file descriptor for con0. Am i missing something in my
rootfs?
$ uml_mconsole VoTvJ8 config con0
OK fd:0

Attaching the stdout from running below cmd
$./linux ubd0=../rootfs mem=256M


Thanks,
Ashwanth

Re: [uml-user] [PATCH] um: asm/page.h: zero out a pte's high value in set_pte_val()

[Richard W. <ri...@no...>]

Am 29.01.2016 um 15:31 schrieb Nicolai Stange:
>>> Question 1: now that ->pte_high will be gone, do you want to have
>>>             ->pte_low renamed to e.g. ->pte_val?
>>
>> So, with a freshly booted brain the story looks a bit different.
>> All this code needs a cleanup and we need to check what other archs do
>> before we change pte_val(). Are you ready for some research? :)
> 
> So this is what arch/x86 does:
> 
> 1.) typedef a pteval_t to a type matching the underlying hardware's
>     native PTE size.
>     Examples:
>     - x86: arch/x86/include/asm/pgtable-2level_types.h -- unsigned long
>     - x86(PAE): arch/x86/include/asm/pgtable-3level_types.h -- u64
>     - x86_64: arch/x86/include/asm/pgtable_64_types.h -- unsigned long
> 
> 2.) pte_t is typedefed to either a struct or union like this:
> 
>       typedef struct { pteval_t pte; } pte_t;
> 
>     In the case of a union (x86 and x86 w/ PAE), an additional member
>     'pte_low' is introduced, aliasing the low half of ->pte.
> 
> Now, all three x86-arch cases define typedef a pgprotval_t matching their
> respective pteval_t type and have a common then
> 
>   typedef struct pgprot { pgprotval_t pgprot; } pgprot_t;
> 
> Basically, mk_pte(page, pgprot) shifts the page's physical address to
> some architecturally defined point (PAGE_SHIFT) within pteval_t and ors
> the architecturally defined protection flags (_PAGE_*) in.
> 
> Of course, the protection flags are defined such that hardware
> eventually finds them at the expected place within the final PTE
> (c.f. arch/x86/include/asm/pgtable_types.h).
> 
> 
> Summarizing:
> The content of pteval_t is completely architecture dependent.  The only
> semantics on pte values defined for out-of-arch users, e.g. mm/gup.c
> seems to be equality on a pte_val(pte).
> 

Thanks for doing the research!

> Finally, the page protection flags defined for UML do not have any bit
> at a position greater than 9 assigned to them
> (c.g. arch/um/include/asm/pgtable.h). (If that had been the case, we had
> been in trouble already because protection flags are only or'ed into
> ->pte_low).
> 
> 
> Thus, under the assumption that with UML, physical addresses are always
> 32 bits, I would say that it is safe to change pte_t.
> 
> 
> Proposal:
> Introduce pteval_t and pgprotval_t like x86 does and do
> 
>   typedef struct { pteval_t pte; } pte_t;
>   typedef struct pgprot { pgprotval_t pgprot; } pgprot_t;
> 
> Change the pte macros accordingly.

Makes sense.

> What about pgd_t and pmd_t?

What do you mean? AFAICT we can keep them as-is.

So, please redo your patch such that we can merge it as soon as possible
to have the build warning fixed.

Thanks,
//richard

Re: [uml-user] [PATCH] um: asm/page.h: zero out a pte's high value in set_pte_val()

[Richard W. <ri...@no...>]

Am 29.01.2016 um 02:32 schrieb Nicolai Stange:
> Richard Weinberger <ri...@no...> writes:
> 
>> Am 29.01.2016 um 00:56 schrieb Nicolai Stange:
>>> Commit 16da306849d0 ("um: kill pfn_t")
>>> introduced a compile warning for defconfig:
>>>
>>>   arch/um/kernel/skas/mmu.c:38:206: warning: right shift count >= width of type
>>>                                     [-Wshift-count-overflow]
>>>
>>> Aforementioned patch changes the definition of the phys_to_pfn() macro from
>>>
>>>   ((pfn_t) ((p) >> PAGE_SHIFT))
>>>
>>> to
>>>
>>>   ((p) >> PAGE_SHIFT)
>>>
>>> This effectively changes the phys_to_pfn() expansion's type from
>>> unsigned long long to unsigned long.
>>>
>>> Through the callchain init_stub_pte()->mk_pte(), the expansion of
>>> phys_to_pfn() is (indirectly) fed into the 'phys' argument of the
>>> pte_set_val(pte, phys, prot) macro, eventually leading to
>>>
>>>   (pte).pte_high = (phys) >> 32;
>>>
>>> This results in the warning from above.
>>>
>>> Since UML only deals with 32 bit addresses, the upper 32 bits from 'phys'
>>> used to be zero anyway.
>>>
>>> Zero out the pte value's high part in pte_set_val() in order to get rid
>>> of the offending shift.
>>>
>>> Fixes: 16da306849d0 ("um: kill pfn_t")
>>> Signed-off-by: Nicolai Stange <nic...@gm...>
>>> ---
>>>  arch/um/include/asm/page.h | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/um/include/asm/page.h b/arch/um/include/asm/page.h
>>> index e13d41c..61e235f 100644
>>> --- a/arch/um/include/asm/page.h
>>> +++ b/arch/um/include/asm/page.h
>>> @@ -46,8 +46,8 @@ typedef struct { unsigned long pgd; } pgd_t;
>>>  			      smp_wmb(); \
>>>  			      (to).pte_low = (from).pte_low; })
>>>  #define pte_is_zero(pte) (!((pte).pte_low & ~_PAGE_NEWPAGE) && !(pte).pte_high)
>>> -#define pte_set_val(pte, phys, prot) \
>>> -	({ (pte).pte_high = (phys) >> 32; \
>>> +#define pte_set_val(pte, phys, prot)				\
>>> +	({ (pte).pte_high = 0;					\
>>>  	   (pte).pte_low = (phys) | pgprot_val(prot); })
>>
>> I think we can completely kill .pte_high.
>>
> 
> I did a quick test with ->pte_high purged and this doesn't introduce any
> new warnings.
> 
> Booting w/o a rootfs works up to mount_root.
> 
> 
> Note that an implication of getting rid of ->pte_high would be that the
> type of pte_val() would get changed from unsigned long long to unsigned
> long. However, outside of arch/um, pte_val() is only used here:
> - drivers/gpu/drm/drm_vm.c
> - include/trace/events/xen.h
> - mm/gup.c
> - mm/memory.c
> All these uses and the ones in arch/um itself look compatible with this
> change (if relevant at all for UML).
> 
> 
> I'll post a follow up patch for this tomorrow.
> 
> Question 1: now that ->pte_high will be gone, do you want to have
>             ->pte_low renamed to e.g. ->pte_val?

So, with a freshly booted brain the story looks a bit different.
All this code needs a cleanup and we need to check what other archs do
before we change pte_val(). Are you ready for some research? :)

> Question 2: what is the smp_wmb() in pte_copy() paired with/good for?

AFACT to make sure that a write to pte_high is complete before we write pte_low.
100% copy&pasted from arch/i386 15 years ago. ;-)

Thanks,
//richard

Re: [uml-user] [PATCH] um: asm/page.h: zero out a pte's high value in set_pte_val()

[Richard W. <ri...@no...>]

Am 29.01.2016 um 00:56 schrieb Nicolai Stange:
> Commit 16da306849d0 ("um: kill pfn_t")
> introduced a compile warning for defconfig:
> 
>   arch/um/kernel/skas/mmu.c:38:206: warning: right shift count >= width of type
>                                     [-Wshift-count-overflow]
> 
> Aforementioned patch changes the definition of the phys_to_pfn() macro from
> 
>   ((pfn_t) ((p) >> PAGE_SHIFT))
> 
> to
> 
>   ((p) >> PAGE_SHIFT)
> 
> This effectively changes the phys_to_pfn() expansion's type from
> unsigned long long to unsigned long.
> 
> Through the callchain init_stub_pte()->mk_pte(), the expansion of
> phys_to_pfn() is (indirectly) fed into the 'phys' argument of the
> pte_set_val(pte, phys, prot) macro, eventually leading to
> 
>   (pte).pte_high = (phys) >> 32;
> 
> This results in the warning from above.
> 
> Since UML only deals with 32 bit addresses, the upper 32 bits from 'phys'
> used to be zero anyway.
> 
> Zero out the pte value's high part in pte_set_val() in order to get rid
> of the offending shift.
> 
> Fixes: 16da306849d0 ("um: kill pfn_t")
> Signed-off-by: Nicolai Stange <nic...@gm...>
> ---
>  arch/um/include/asm/page.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/um/include/asm/page.h b/arch/um/include/asm/page.h
> index e13d41c..61e235f 100644
> --- a/arch/um/include/asm/page.h
> +++ b/arch/um/include/asm/page.h
> @@ -46,8 +46,8 @@ typedef struct { unsigned long pgd; } pgd_t;
>  			      smp_wmb(); \
>  			      (to).pte_low = (from).pte_low; })
>  #define pte_is_zero(pte) (!((pte).pte_low & ~_PAGE_NEWPAGE) && !(pte).pte_high)
> -#define pte_set_val(pte, phys, prot) \
> -	({ (pte).pte_high = (phys) >> 32; \
> +#define pte_set_val(pte, phys, prot)				\
> +	({ (pte).pte_high = 0;					\
>  	   (pte).pte_low = (phys) | pgprot_val(prot); })

I think we can completely kill .pte_high.

Thanks,
//richard

Re: [uml-user] [PATCH] um: use %lx format specifiers for unsigned longs

[Richard W. <ri...@no...>]

Am 23.01.2016 um 20:17 schrieb Colin King:
> From: Colin Ian King <col...@ca...>
> 
> static analysis from cppcheck detected %x being used for
> unsigned longs:
> 
> [arch/x86/um/os-Linux/task_size.c:112]: (warning) %x in format
>   string (no. 1) requires 'unsigned int' but the argument type
>   is 'unsigned long'.
> 
> Use %lx instead of %x
> 
> Signed-off-by: Colin Ian King <col...@ca...>

Applied, Thanks!
//richard

[uml-user] [PATCH] Revert "um: Fix get_signal() usage"

[Richard W. <ri...@no...>]

Commit db2f24dc240856fb1d78005307f1523b7b3c121b
was plain wrong. I did not realize the we are
allowed to loop here.
In fact we have to loop and must not return to userspace
before all SIGSEGVs have been delivered.
Other archs do this directly in their entry code, UML
does it here.

Reported-by: Al Viro <vi...@ze...>
Signed-off-by: Richard Weinberger <ri...@no...>

diff --git a/arch/um/kernel/signal.c b/arch/um/kernel/signal.c
index fc8be0e..57acbd6 100644
--- a/arch/um/kernel/signal.c
+++ b/arch/um/kernel/signal.c
@@ -69,7 +69,7 @@ void do_signal(struct pt_regs *regs)
 	struct ksignal ksig;
 	int handled_sig = 0;
 
-	if (get_signal(&ksig)) {
+	while (get_signal(&ksig)) {
 		handled_sig = 1;
 		/* Whee!  Actually deliver the signal.  */
 		handle_signal(&ksig, regs);
-- 
1.8.4.5

[uml-user] [PATCH 22/22] um: Export pm_power_off

[Richard W. <ri...@no...>]

...modules are using this symbol.
Export it like all other archs to.

Signed-off-by: Richard Weinberger <ri...@no...>
---
 arch/um/kernel/reboot.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/um/kernel/reboot.c b/arch/um/kernel/reboot.c
index 9bdf67a..b60a9f8 100644
--- a/arch/um/kernel/reboot.c
+++ b/arch/um/kernel/reboot.c
@@ -12,6 +12,7 @@
 #include <skas.h>
 
 void (*pm_power_off)(void);
+EXPORT_SYMBOL(pm_power_off);
 
 static void kill_off_processes(void)
 {
-- 
1.8.4.5

[uml-user] reboot guest OS ??? is it possible ?

[<mr...@fr...>]

Hello all,

I recently investigate on UML, and i have a little issue with the way system
reboots. (btw i dont know if this the way to go *really*)

My config is for host: debian jessie out of the box..
for guest OS i try several kernel and filesytstem but both hangs with the same
issues:
FS1 : debootstraped fs from Debian jessie
FS2 : devloop.org.uk filesystem Debian jessie.

Kernel1: 3.16 custom compiled kernel (.config from devloop.uk.org)
Kernel2: linux.uml debian kernel from package user-mode-linux
Kernel3: compiled devloop.uk.org kernel 3.18

if i launch 1 station and reboot from the guest OS shell, i saw on the host a
uml_watchdog process that seems to kill my guest OS few seconds after...

I cant find any documentation concerning this uml_watchdog, can't figure out how
it spawn from guest OS reboot...

but i am quite sure it is the culprit since copying /bin/true
to /usr/bin/uml_watchdog solve the issue... however i still have defunct process
(ex uml_watchdog).

The source of this uml_watchdog.c i found on internet doesnt make me much sense
since it looks like just looking from input on stdin ?.

Btw UML Watchdog timer is enabled on the guest OS.. not sure it is correctly
running since the quest OS complains about error on device 130 which is
/dev/watchdog

Does anyone have clue about uml_watchdog ???

I definitively think reboot somewhere else from uml_mconsole is a *BAD* idea....

more coming....


Trying to share the same root filesystem on 2 UML:

linux.uml ubda=/tmp/m1.cow,./filesystem mem=256M con0=fd:0,fd:1 con=null
linux.uml ubda=/tmp/m2.cow,./filesystem mem=256M con0=fd:0,fd:1 con=null


if i launch these 2 stations and reboot them from shell at the same time, one
hang, the other reboot fine.

and as usual it looks ok if i do this from uml_mconsole xxx reboot .

The bad news is that i would like to give user the opportunity to rebbot a guest
OS without giving access to the host....

Any help greatly apprciated, since i spend much time trying to debug this issue.
I can still do further investigation...

Thx

Re: [uml-user] Anyone there?

[Balaco B. <bal...@im...>]

May someone please make any comments about my message and situation?
Richard?

-- 
  Balaco



On Thu, Dec 10, 2015, at 16:45, Balaco Baco wrote:
> On Mon, Nov 23, 2015, at 19:15, Balaco Baco wrote:
> > On Mon, Nov 23, 2015, at 18:32, Richard Weinberger wrote:
> > > Am 23.11.2015 um 22:31 schrieb Balaco Baco:
> > > > I skimmed though it. To use ping to test if Internet connections are
> > > > working or not is one the most basic things everybody does and learn.
> > > > If, in some exotic setup (like UML's) makes this different, it should
> > > > say so, clearly (and not "indirectly obvious"). There are more than 15
> > > > years I have done and seen ping being used to test connections.
> > > > 
> > > > ... now I must do this! I'm barely believing it... BRB... - if it does
> > > > not work only! :P hahaha
> > > > 
> > > 
> > > Again, this has 0 to do with UML, with qemu's user networking, which is
> > > based
> > > on SLIRP, it is the same...
> > 
> > I don't understand these things much more than knowing their names and
> > what it does.
> > 
> > (...)
> > 
> > :(
> > 
> > Believe it or not, It still does not work: 
> > 
> > ==============
> > $ apt-get download vim
> > Err Downloading vim 2:7.3.547-7     
> >   Temporary failure resolving 'ftp.fr.debian.org'
> > ==============
> > 
> > And /etc/resolv.conf has the same contents of the host's file.
> > 
> > The command ifconfig gives:
> > ====================
> > $ ifconfig
> > eth0      Link encap:Serial Line IP  
> >           inet addr:10.0.2.15  Mask:255.0.0.0
> >           UP RUNNING NOARP  MTU:1500  Metric:1
> >           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> >           TX packets:125 errors:0 dropped:0 overruns:0 carrier:0
> >           collisions:0 txqueuelen:256 
> >           RX bytes:0 (0.0 B)  TX bytes:10296 (10.0 KiB)
> >           Interrupt:5 
> > 
> > lo        Link encap:Local Loopback  
> >           inet addr:127.0.0.1  Mask:255.0.0.0
> >           UP LOOPBACK RUNNING  MTU:65536  Metric:1
> >           RX packets:26 errors:0 dropped:0 overruns:0 frame:0
> >           TX packets:26 errors:0 dropped:0 overruns:0 carrier:0
> >           collisions:0 txqueuelen:0 
> >           RX bytes:2004 (1.9 KiB)  TX bytes:2004 (1.9 KiB)
> > ====================
> > 
> > Makeing a wget with IPs (I copied manually) also don't work:
> > 
> > =======================
> > $  wget ftp://208.118.235.20/gnu/bison/bison-1.25.tar.gz
> > --2015-11-23 22:10:02-- 
> > ftp://208.118.235.20/gnu/bison/bison-1.25.tar.gz
> >            => `bison-1.25.tar.gz'
> > Connecting to 208.118.235.20:21... failed: Connection timed out.
> > Retrying.
> > 
> > --2015-11-23 22:12:11-- 
> > ftp://208.118.235.20/gnu/bison/bison-1.25.tar.gz
> >   (try: 2) => `bison-1.25.tar.gz'
> > Connecting to 208.118.235.20:21... 
> > 
> > # Minutes pass without any better output. The file is just 280KiB, it
> > could have
> > # been downloaded with a dial up connection (so the slowness of Slirp
> > surely is
> > # not the case here).
> > =======================
> > 
> > I don't know what else would be useful for you. I would try SSH but it's
> > not installed now in the my Debian (which was download from some UML related page, by the way).
> > 
> > How can I make DNS work, then?
> > 
> > 
> 
> Anyone there? I'm stopped since the last message (above here), waiting
> for someone to tell me what I have missed or anything. I have no clues
> on what I should do here. Please say anything.
> 
> Thank you,
> 
> -- 
>   Balaco
> 
> 
> 
> 
> -- 
> http://www.fastmail.com - Email service worth paying for. Try it for
> free
> 
> -- 
>   Balaco
> 
> 
> -- 
> http://www.fastmail.com - The professional email service
> 
> 
> ------------------------------------------------------------------------------
> _______________________________________________
> User-mode-linux-user mailing list
> Use...@li...
> https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user

-- 
http://www.fastmail.com - mmm... Fastmail...

Re: [uml-user] [PATCH v5 0/2] um: Protect memory mapped file

[Richard W. <ri...@no...>]

Am 22.12.2015 um 22:15 schrieb Mickaël Salaün:
> This series protect the memory mapped file. This apply on v4.4-rc6.
> 
> Changes since v4:
> * fix spelling [1/2]
> 
> Changes since v3:
> * add Tristan Schmelcher's ack
> 
> Changes since v2; addressed Tristan Schmelcher's comment:
> * remove the whole fchmod call [1/2]
> 
> Changes since v1; addressed Richard Weinberger's comments:
> * add attacker model to the patch description [1/2]
> * remove errno reset [2/2]
> 
> Regards,
>  Mickaël
> 
> Mickaël Salaün (2):
>   um: Do not set unsecure permission for temporary file
>   um: Use race-free temporary file creation

Applied!

Thanks,
//richard

Re: [uml-user] Anyone there?

[Balaco B. <bal...@im...>]

On Mon, Nov 23, 2015, at 19:15, Balaco Baco wrote:
> On Mon, Nov 23, 2015, at 18:32, Richard Weinberger wrote:
> > Am 23.11.2015 um 22:31 schrieb Balaco Baco:
> > > I skimmed though it. To use ping to test if Internet connections are
> > > working or not is one the most basic things everybody does and learn.
> > > If, in some exotic setup (like UML's) makes this different, it should
> > > say so, clearly (and not "indirectly obvious"). There are more than 15
> > > years I have done and seen ping being used to test connections.
> > > 
> > > ... now I must do this! I'm barely believing it... BRB... - if it does
> > > not work only! :P hahaha
> > > 
> > 
> > Again, this has 0 to do with UML, with qemu's user networking, which is
> > based
> > on SLIRP, it is the same...
> 
> I don't understand these things much more than knowing their names and
> what it does.
> 
> (...)
> 
> :(
> 
> Believe it or not, It still does not work: 
> 
> ==============
> $ apt-get download vim
> Err Downloading vim 2:7.3.547-7     
>   Temporary failure resolving 'ftp.fr.debian.org'
> ==============
> 
> And /etc/resolv.conf has the same contents of the host's file.
> 
> The command ifconfig gives:
> ====================
> $ ifconfig
> eth0      Link encap:Serial Line IP  
>           inet addr:10.0.2.15  Mask:255.0.0.0
>           UP RUNNING NOARP  MTU:1500  Metric:1
>           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:125 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:256 
>           RX bytes:0 (0.0 B)  TX bytes:10296 (10.0 KiB)
>           Interrupt:5 
> 
> lo        Link encap:Local Loopback  
>           inet addr:127.0.0.1  Mask:255.0.0.0
>           UP LOOPBACK RUNNING  MTU:65536  Metric:1
>           RX packets:26 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:26 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0 
>           RX bytes:2004 (1.9 KiB)  TX bytes:2004 (1.9 KiB)
> ====================
> 
> Makeing a wget with IPs (I copied manually) also don't work:
> 
> =======================
> $  wget ftp://208.118.235.20/gnu/bison/bison-1.25.tar.gz
> --2015-11-23 22:10:02-- 
> ftp://208.118.235.20/gnu/bison/bison-1.25.tar.gz
>            => `bison-1.25.tar.gz'
> Connecting to 208.118.235.20:21... failed: Connection timed out.
> Retrying.
> 
> --2015-11-23 22:12:11-- 
> ftp://208.118.235.20/gnu/bison/bison-1.25.tar.gz
>   (try: 2) => `bison-1.25.tar.gz'
> Connecting to 208.118.235.20:21... 
> 
> # Minutes pass without any better output. The file is just 280KiB, it
> could have
> # been downloaded with a dial up connection (so the slowness of Slirp
> surely is
> # not the case here).
> =======================
> 
> I don't know what else would be useful for you. I would try SSH but it's
> not installed now in the my Debian (which was download from some UML related page, by the way).
> 
> How can I make DNS work, then?
> 
> 

Anyone there? I'm stopped since the last message (above here), waiting
for someone to tell me what I have missed or anything. I have no clues
on what I should do here. Please say anything.

Thank you,

-- 
  Balaco




-- 
http://www.fastmail.com - Email service worth paying for. Try it for
free

-- 
  Balaco


-- 
http://www.fastmail.com - The professional email service

Re: [uml-user] Anyone there?

[Balaco B. <bal...@im...>]

On Mon, Nov 23, 2015, at 19:15, Balaco Baco wrote:
> On Mon, Nov 23, 2015, at 18:32, Richard Weinberger wrote:
> > Am 23.11.2015 um 22:31 schrieb Balaco Baco:
> > > I skimmed though it. To use ping to test if Internet connections are
> > > working or not is one the most basic things everybody does and learn.
> > > If, in some exotic setup (like UML's) makes this different, it should
> > > say so, clearly (and not "indirectly obvious"). There are more than 15
> > > years I have done and seen ping being used to test connections.
> > > 
> > > ... now I must do this! I'm barely believing it... BRB... - if it does
> > > not work only! :P hahaha
> > > 
> > 
> > Again, this has 0 to do with UML, with qemu's user networking, which is
> > based
> > on SLIRP, it is the same...
> 
> I don't understand these things much more than knowing their names and
> what it does.
> 
> (...)
> 
> :(
> 
> Believe it or not, It still does not work: 
> 
> ==============
> $ apt-get download vim
> Err Downloading vim 2:7.3.547-7     
>   Temporary failure resolving 'ftp.fr.debian.org'
> ==============
> 
> And /etc/resolv.conf has the same contents of the host's file.
> 
> The command ifconfig gives:
> ====================
> $ ifconfig
> eth0      Link encap:Serial Line IP  
>           inet addr:10.0.2.15  Mask:255.0.0.0
>           UP RUNNING NOARP  MTU:1500  Metric:1
>           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:125 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:256 
>           RX bytes:0 (0.0 B)  TX bytes:10296 (10.0 KiB)
>           Interrupt:5 
> 
> lo        Link encap:Local Loopback  
>           inet addr:127.0.0.1  Mask:255.0.0.0
>           UP LOOPBACK RUNNING  MTU:65536  Metric:1
>           RX packets:26 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:26 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0 
>           RX bytes:2004 (1.9 KiB)  TX bytes:2004 (1.9 KiB)
> ====================
> 
> Makeing a wget with IPs (I copied manually) also don't work:
> 
> =======================
> $  wget ftp://208.118.235.20/gnu/bison/bison-1.25.tar.gz
> --2015-11-23 22:10:02-- 
> ftp://208.118.235.20/gnu/bison/bison-1.25.tar.gz
>            => `bison-1.25.tar.gz'
> Connecting to 208.118.235.20:21... failed: Connection timed out.
> Retrying.
> 
> --2015-11-23 22:12:11-- 
> ftp://208.118.235.20/gnu/bison/bison-1.25.tar.gz
>   (try: 2) => `bison-1.25.tar.gz'
> Connecting to 208.118.235.20:21... 
> 
> # Minutes pass without any better output. The file is just 280KiB, it
> could have
> # been downloaded with a dial up connection (so the slowness of Slirp
> surely is
> # not the case here).
> =======================
> 
> I don't know what else would be useful for you. I would try SSH but it's
> not installed now in the my Debian (which was download from some UML related page, by the way).
> 
> How can I make DNS work, then?
> 
> 

Anyone there? I'm stopped since the last message (above here), waiting
for someone to tell me what I have missed or anything. I have no clues
on what I should do here. Please say anything.

Thank you,

-- 
  Balaco




-- 
http://www.fastmail.com - Email service worth paying for. Try it for free

Re: [uml-user] [PATCH v2 1/2] um: Set secure access mode for temporary file

[Richard W. <ri...@no...>]

Am 08.12.2015 um 21:37 schrieb Tristan Schmelcher:
> On 6 December 2015 at 09:43, Mickaël Salaün <mi...@di...> wrote:
>> Well, I'm concerned to use umask because it is not thread-safe and drivers may use create_mem_file() in a multi-theaded context.
> 
> You are right. We should perhaps set the umask to 0700 permanently
> during process start. But I am not sure if this will interfere with
> other UML code.

It *should* not hurt. Let's see what explodes. :)

>> I prefer to stick to fchmod and handle the race-condition with O_TMPFILE unsell someone is sure that this will not create bugs :)
> 
> The fchmod call is basically useless and should probably be removed.

I agree.

Thanks,
//richard