[Qemu-devel] qemu-user + networking issues / segfaults

[Christof Schulze <christof.schulze@gmx.net>]

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Hello qemu-devel list,

This is my first post to this list and I am not sure whether this
actually is the correct Mailinglist.  I recently compiled qemu-1.6.0
on an arm platform for the purpose of running the binary only
otrdecoder-software which is available for a 64bit linux only. I
pursued the following steps:
* creating a chroot on my x64-box that contained the otrdecoder and
  all libraries it needs to run
* test-run the otrdecoder from within the chroot (it works)
* copying this chroot to my arm box, where I compiled qemu previously
* copying qemu and all required libs to the chroot
* copying a shell to the chroot
* copying libnss* libraries from my 64bit system and from my arm
  system to the chroot
* test network connectivity from within the chroot using native
  nslookup and native ping (it works)
* from within the chroot I ran the otrdecoder using qemu-x86_64 which
  works up to a point where it segfaults.
  
running qemu using the -strace flag and comparing the output with a
successful strace from my 64bit-box reveals that the segfault happens
after an munmap and before (or at) the spot where a socket() operation
is run.

This is the operation that should be run:
socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 3

I am not sure if qemu segfaults because 
* there are actually libs missing in the chroot 
* the syscall is not supported
* the binary does crazy things and is not supported by qemu-user
  
At the same time running the 64bit version of ping results in a
segfault as well which might be related.

this is what the segfault of the otrdecoder shows:
--- SIGSEGV (Segmentation fault) @ 0 (0) ---
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
SYS_369(0, 0x4, 0, 0xbe9f6d48, 0x4)     = 0
SYS_369(0, 0x4, 0, 0xbe9f8dd8, 0x4)     = 0
SYS_369(0, 0x4, 0xbe9f8dd8, 0, 0xbe9f8dd8) = 0
futex(0xb6dcf7d0, FUTEX_WAKE_PRIVATE, 2147483647) = 0
write(2, "qemu: uncaught target signal 11 "..., 67qemu: uncaught target signal 
11 (Segmentation fault) - core dumped
) = 67
rt_sigaction(SIGSEGV, {SIG_DFL, ~[RTMIN RT_1], SA_INTERRUPT|SA_NODEFER|
0x5199d28}, NULL, 8) = 0
kill(30161, SIGSEGV)                    = 0
--- SIGSEGV (Segmentation fault) @ 0 (0) ---
+++ killed by SIGSEGV +++

What can I do to investigate further and get this fixed besides trying
to emulate a full-blown system?

Christof

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