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[uml-devel] null stdin/stdout strangeness - but getting there!
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From: William S. <wst...@po...> - 2000-11-07 19:54:23
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Good day, Jeff and all,
(Host 2.4.0-test10, rh7, uml root is rh62)
Thanks for the infinite printk fix, Jeff. The printk meltdown
found in previous versions ("Hmmm, can't printk that message? Must alert
the user with a printk!") has disappeared.
I'm trying to run test10 with stdin and stdout redirected from/to
/dev/null - I'm hoping to use it as a server only platform. When I use
e2fsck -v -y root_fs ; ./linux-2.4.0-test10 mem=48M </dev/null
the boot proceeds pretty well until it gets to the named boot
script. If I don't use the </dev/null, umnl boots to xterms and a login
prompt. Once I add </dev/null, it stops somewhere in the named script (a
"ping the hotst" script run before named executes, one run after named
does not).
Partway through that script, fd0 is completely closed on all uml
threads. I can watch it with:
while /bin/true ; do clear ; for X in $(ps axf | grep [l]inux-2.4.0-test10
| awk '{print $1}') ; do ls -al /proc/$X/fd/0 ; done ; sleep 1 ; done
Up until named, I get:
lr-x------ 1 wstearns wstearns 64 Nov 7 14:31 /proc/25751/fd/0 -> /dev/null
lr-x------ 1 wstearns wstearns 64 Nov 7 14:31 /proc/25752/fd/0 -> /dev/null
lr-x------ 1 wstearns wstearns 64 Nov 7 14:31 /proc/25763/fd/0 -> /dev/null
...
lr-x------ 1 wstearns wstearns 64 Nov 7 14:31 /proc/25865/fd/0 -> /dev/null
lr-x------ 1 wstearns wstearns 64 Nov 7 14:31 /proc/25884/fd/0 -> /dev/null
lr-x------ 1 wstearns wstearns 64 Nov 7 14:31 /proc/25920/fd/0 -> /dev/null
with the odd "No such file or directory" from the delay between
looking up the pids and actually taking a dir. Once the named script gets
underway, all threads no longer have stdin open:
ls: /proc/26443/fd/0: No such file or directory
ls: /proc/25751/fd/0: No such file or directory
ls: /proc/25752/fd/0: No such file or directory
ls: /proc/25763/fd/0: No such file or directory
ls: /proc/25768/fd/0: No such file or directory
ls: /proc/25769/fd/0: No such file or directory
ls: /proc/25764/fd/0: No such file or directory
ls: /proc/25765/fd/0: No such file or directory
ls: /proc/25766/fd/0: No such file or directory
ls: /proc/25767/fd/0: No such file or directory
ls: /proc/25795/fd/0: No such file or directory
ls: /proc/25828/fd/0: No such file or directory
ls: /proc/25884/fd/0: No such file or directory
ls: /proc/25920/fd/0: No such file or directory
ls: /proc/26074/fd/0: No such file or directory
ls: /proc/26266/fd/0: No such file or directory
ls: /proc/26319/fd/0: No such file or directory
ls: /proc/26330/fd/0: No such file or directory
ls: /proc/26345/fd/0: No such file or directory
ls: /proc/26346/fd/0: No such file or directory
ls: /proc/26347/fd/0: No such file or directory
ls: /proc/26348/fd/0: No such file or directory
ls: /proc/26349/fd/0: No such file or directory
ls: /proc/26365/fd/0: No such file or directory
ls: /proc/26381/fd/0: No such file or directory
ls: /proc/26385/fd/0: No such file or directory
ls: /proc/26397/fd/0: No such file or directory
ls: /proc/26398/fd/0: No such file or directory
For the brief second between when the network is brought up and
when fd0 is closed, I can ping uml from the host. Once fd0 is closed, I
can't anymore. I'll guess that named isn't itself the problem; it just
happens to be executing and trying to do outside lookups when the fd is
closed:
tcpdump: listening on tap1
14:47:51.592086 B arp who-has uml-router tell 192.168.210.141
14:47:51.592101 > arp reply uml-router (fe:fd:0:0:0:0) is-at fe:fd:0:0:0:0 (fe:fd:c0:a8:d2:8d)
14:47:51.597167 < 192.168.210.141.1024 > a.root-servers.net.domain: 31496 NS? . (17) (DF)
14:47:51.842545 > a.root-servers.net.domain > 192.168.210.141.1024: 31496*- 13/0/13 NS A.ROOT-SERVERS.NET., NS H.ROOT-SERVERS.NET., NS C.ROOT-SERVERS.NET., NS G.ROOT-SERVERS.NET., NS F.ROOT-SERVERS.NET., (436)
14:47:55.006502 < 192.168.210.141.1024 > d.root-servers.net.domain: 31496 NS? . (17) (DF)
14:47:55.532558 > d.root-servers.net.domain > 192.168.210.141.1024: 31496*- 13/0/13 NS C.ROOT-SERVERS.NET., NS G.ROOT-SERVERS.NET., NS F.ROOT-SERVERS.NET., NS B.ROOT-SERVERS.NET., NS J.ROOT-SERVERS.NET., (436)
14:47:59.007525 < 192.168.210.141.1024 > k.root-servers.net.domain: 31496 NS? . (17) (DF)
14:47:59.302574 > k.root-servers.net.domain > 192.168.210.141.1024: 31496*- 13/0/13 NS K.ROOT-SERVERS.NET., NS L.ROOT-SERVERS.NET., NS M.ROOT-SERVERS.NET., NS I.ROOT-SERVERS.NET., NS E.ROOT-SERVERS.NET., (436)
It looks like the responses are being passed back to the uml
correctly. (Note that the host is doing Masq/NAT for the uml).
I'm not sure if these are all just symptoms of some other problem
or even if a closed fd0 matters. I'm bringing it up on the off chance
that close is being called accidentally in one of the uml threads, or
being called correctly but with an incorrect parameter of 0.
Just for reference, here are the fd's for the parent tracing
thread once it's stopped at named:
[root@sparrow rh6.2]# ls -al /proc/29904/fd
total 8
dr-x------ 2 wstearns wstearns 0 Nov 7 14:45 .
dr-xr-xr-x 3 wstearns wstearns 0 Nov 7 14:45 ..
lrwx------ 1 wstearns wstearns 64 Nov 7 14:45 1 -> /dev/pts/8
lrwx------ 1 wstearns wstearns 64 Nov 7 14:45 10 -> /home/wstearns/uml/rh6.2/root_fs
lrwx------ 1 wstearns wstearns 64 Nov 7 14:45 11 -> socket:[12210072]
lrwx------ 1 wstearns wstearns 64 Nov 7 14:45 2 -> /dev/pts/8
lrwx------ 1 wstearns wstearns 64 Nov 7 14:45 3 -> /home/wstearns/uml/rh6.2/vm_file (deleted)
lrwx------ 1 wstearns wstearns 64 Nov 7 14:45 4 -> /home/wstearns/uml/rh6.2/vm_file (deleted)
lrwx------ 1 wstearns wstearns 64 Nov 7 14:45 5 -> /home/wstearns/uml/rh6.2/vm_file (deleted)
lrwx------ 1 wstearns wstearns 64 Nov 7 14:45 6 -> /home/wstearns/uml/rh6.2/vm_file (deleted)
lrwx------ 1 wstearns wstearns 64 Nov 7 14:45 7 -> /dev/ptyp0
lrwx------ 1 wstearns wstearns 64 Nov 7 14:45 8 -> /dev/ptmx
lrwx------ 1 wstearns wstearns 64 Nov 7 14:45 9 -> /dev/pts/20
Cheers,
- Bill 'eating red herrings again for dinner?' Stearns
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"Assuming that piece of ear weighed about 1/2 an ounce, Bill
[Gates] could afford to eat 443.39 pounds of Evander Holyfield if he were
so inclined."
-=- http://web.quuxuum.org/~evan/bgnw.html
(Courtesy of James Mastros <ro...@je...>)
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William Stearns (wst...@po...). Mason, Buildkernel, named2hosts,
and ipfwadm2ipchains are at: http://www.pobox.com/~wstearns
LinuxMonth; articles for Linux Enthusiasts! http://www.linuxmonth.com
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