Re: [uml-devel] UML/64bit is miscompiled by gcc 4.0.3 on Ubuntu 6.06 LTS

[Blaisorblade <blaisorblade@yahoo.it>]

On Wednesday 17 January 2007 19:17, Christopher S. Aker wrote:
> Blaisorblade wrote:
> [snip]
>
> > Without any errors, after these messages:
> >
> > kjournald starting.  Commit interval 5 seconds
> > EXT3-fs: mounted filesystem with ordered data mode.
> > VFS: Mounted root (ext3 filesystem) readonly.
> >
> > it hangs giving the following result at strace -p (I've printed two
> > consecutive iterations of the same messages to show that they are the
> > same):
> >
> > --- SIGCHLD (Child exited) @ 0 (0) ---
> > wait4(31586, [{WIFSTOPPED(s) && WSTOPSIG(s) == SIGSEGV}], WSTOPPED, NULL)
> > = 31586
> > ptrace(PTRACE_GETREGS, 31586, 0, 0x6096dac8) = 0
> > ptrace(PTRACE_GETFPREGS, 31586, 0, 0x6096dba0) = 0
> > ptrace(PTRACE_CONT, 31586, 0, SIGSEGV)  = 0
> > --- SIGCHLD (Child exited) @ 0 (0) ---
> > wait4(31586, [{WIFSTOPPED(s) && WSTOPSIG(s) == SIGUSR1}], WSTOPPED, NULL)
> > = 31586
> > ptrace(PTRACE_SETREGS, 31586, 0, 0x6096dac8) = 0
> > ptrace(PTRACE_SETFPREGS, 31586, 0, 0x6096dba0) = 0
> > ptrace(PTRACE_SYSCALL, 31586, 0, SIG_0) = 0
> >
> > --- SIGCHLD (Child exited) @ 0 (0) ---
> > wait4(31586, [{WIFSTOPPED(s) && WSTOPSIG(s) == SIGSEGV}], WSTOPPED, NULL)
> > = 31586
> > ptrace(PTRACE_GETREGS, 31586, 0, 0x6096dac8) = 0
> > ptrace(PTRACE_GETFPREGS, 31586, 0, 0x6096dba0) = 0
> > ptrace(PTRACE_CONT, 31586, 0, SIGSEGV)  = 0
> > --- SIGCHLD (Child exited) @ 0 (0) ---
> > wait4(31586, [{WIFSTOPPED(s) && WSTOPSIG(s) == SIGUSR1}], WSTOPPED, NULL)
> > = 31586
> > ptrace(PTRACE_SETREGS, 31586, 0, 0x6096dac8) = 0
> > ptrace(PTRACE_SETFPREGS, 31586, 0, 0x6096dba0) = 0
> > ptrace(PTRACE_SYSCALL, 31586, 0, SIG_0) = 0
> >
> > I'll have to verify whether some code in the stubs is miscompiled. But
> > not until... well, I dunno when I'll be back...
> >
> > Anybody else with the same problem?
>
> Isn't this is the same problem we discussed a few months back?  What
> I've discovered since then is this is a regression introduced after
> 2.6.16 on the _host_.  Any post-2.6.16 host kernel, either skas v8.2 or
> v9.pre causes Ubuntu (and other distros, I believe) to hang after "VFS
> mounting root".
Not at all.

I'm running:

64bit host - 2.6.18 on the host, Ubuntu 6.06 LTS. It would use 2.6.15 as 
default kernel, however (which implies their glibc is compiled against it).

Without SKAS.

Guest - 32bit is all fine with Debian (my usual testcase)
- 64bit is fine only with gcc 3.4, with gcc 4.0 I get troubles.

Also, since now I don't have the time to read everything frequently, I start 
forgetting (I used to have a mental db of such problems, when I worked on 
them a lot). We should use http://bugzilla.kernel.org/.

Since both you and Antoine are hitting that same bug, I'm cc'ing both of you.
-- 
Inform me of my mistakes, so I can add them to my list!
Paolo Giarrusso, aka Blaisorblade
http://www.user-mode-linux.org/~blaisorblade
Chiacchiera con i tuoi amici in tempo reale! 
 http://it.yahoo.com/mail_it/foot/*http://it.messenger.yahoo.com 


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