[User-mode-linux-devel] Re: host os 2.3.51 and vm_file - possible clue.

[William S. <wst...@po...>]

Good evening, Jeff,
	OK, so maybe _I_ don't have a clue, but... *smile*

On Sat, 11 Mar 2000, William Stearns wrote:

> 	Host: 2.3.51, shm, devpts, and devfs all mounted.
> 	Linux version 2.3.51-2um, rh62 root_fs (although I don't seem to
> get to the root_fs at all):
> ./linux-2.3.51 devfs=nomount
> ...
> Starting kswapd v1.6
> pty: 256 Unix98 ptys configured
> Initializing stdio console driver
> Initializing software serial port version 0
> Kernel panic: Out of pty's in getmaster (then hang...)
> 
> 	Same effect with 2.3.49, 2.3.49a, and 2.3.50a uml kernels, all on 
> 2.3.51 host.  Hmmm, something wrong with the host kernel?  2.3.51 has
> changes to shm - shared memory, perhaps?  shm is mounted on /var/shm .
> 	I've attached an strace of 2.3.49 trying to start up.  It gives
> the above messages.  The trace seems to be concerned with a file called
> vm_file, so lets try a game:
> [wstearns@sparrow uml]$ touch vm_file
> [wstearns@sparrow uml]$ ./linux-2.3.49 devfs=nomount
> open: File exists
> 	Hmmm - does vm_file have some problem opening on 2.3.51?
> 	I'll play some more.

	OK, more clues.  When I start 2.3.51 as root, it starts:
...
Starting kswapd v1.6
pty: 256 Unix98 ptys configured
Initializing stdio console driver
Initializing software serial port version 0
serial line 0 assigned pty /dev/ptyp0
ssl receive thread is pid 6338
devfs: v0.93 (20000306) Richard Gooch (rg...@at...)
...
	and comes up just fine (well, other details, but I'm looking into
those).  Can anyone else reproduce this?  I'd be happy to provide a trace
of the successful (run as root on host 2.3.51) pass on demand, but in the
interest of brevity, here's the diff of the ends of the traces.  Keep in
mind the first ("-") is 2.3.49, and the second ("+") is 2.3.51.

 lseek(4, 16777216, SEEK_SET)            = 16777216
 write(4, "\0", 1)                       = 1
 old_mmap(0x50000000, 16777216, PROT_READ|PROT_WRITE,MAP_SHARED|MAP_FIXED, 4, 0) = 0x50000000
-fstat(4, {st_mode=S_IFREG|0775, st_size=16777217, ...}) = 0
-mprotect(0x100c8000, 8192, PROT_READ|PROT_WRITE|PROT_EXEC) = 0
+fstat(4, {st_mode=S_IFREG|0755, st_size=16777217, ...}) = 0
+mprotect(0x100d6000, 8192, PROT_READ|PROT_WRITE|PROT_EXEC) = 0
 mprotect(0x50001000, 4096, PROT_READ|PROT_WRITE|PROT_EXEC) = 0
-fn=0x411, child_stack=0x50001ff4, flags=0x7, args=0x1000000clone()                                 = 5671
-rt_sigaction(SIGUSR1, {0x100779dc, [], SA_RESTART}, {SIG_DFL}, 8) = 0
-rt_sigaction(SIGIO, {0x100778b8, [], SA_RESTART}, {SIG_DFL}, 8) = 0
-select(1, [], NULL, NULL, NULL)         = ? ERESTARTNOHAND (To be restarted)
---- SIGUSR1 (User defined signal 1) ---
-kill(5671, SIGUSR1)                     = 0
-sigreturn()                             = ? (mask now [])
-select(2, [0], NULL, NULL, NULL)        = ? ERESTARTNOHAND (To be
restarted)
-+++ killed by SIGKILL +++
+pipe([7, 8])                            = 0
+fn=0x411, child_stack=0x50001ff4, flags=0x7, args=0x1000000clone()                                 = 6429
+rt_sigaction(SIGIO, {0x10084688, [], SA_RESTART}, {SIG_DFL}, 8) = 0
+select(9, [7], NULL, NULL, NULL)        = 1 (in [7])
+read(7, "\2\0\0\0\0\0\0\0\210\264\10\20\4\0\0\0\277\0\0\0000\n\0"...,
140) = 140
+select(9, [0 7], NULL, NULL, NULL
\ No newline at end of file

	Possible relevant differences: the mode on the early fstat,
additional pipe in 2.3.51, SIGUSR1 handler in 2.3.49, perhaps?
	Cheers,
	- Bill

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William Stearns (wst...@po...).  Mason, Buildkernel, named2hosts, 
and ipfwadm2ipchains are at:                http://www.pobox.com/~wstearns
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