Re: XenCD xm save problem: solved by 2.0.4

[Arthur Bergman <abergman@fotango.com>]

On 12 Feb 2005, at 07:56, Jared Rhine wrote:

>
> After fixing this build bug and retrying the resulting XenCD inside
> qemu, xm save/restore now works properly!  (Fresh out of the box (no
> strace xfrd), to both hard disks and tmpfs).
>
> I believe that now every recent report of xm save/restore actually
> works under 2.0.4, while current xen-unstable installations are still
> broken (perhaps in only some cases?)
>

Please try it multiple times

Compiling xfrd with debugging it took my 36 save restore cycles to hit 
the bug. Anything that SLOWS xfrd down seems to fix the bug. Which is 
odd since it is blocking in a read.

Anyway... this is where it is blocking. It seems to be waiting for a 
response that it never gets.

Looking closer at this.

Cheers
Arthur

(gdb) bt
#0  0x402acb48 in read () from /lib/libc.so.6
#1  0x403125e0 in ?? () from /lib/libc.so.6
#2  0x4024e30b in _IO_file_read () from /lib/libc.so.6
#3  0x4024e79f in _IO_file_xsputn () from /lib/libc.so.6
#4  0x4024f4e8 in _IO_sgetn () from /lib/libc.so.6
#5  0x402434b2 in fread () from /lib/libc.so.6
#6  0x0804fb22 in file_read (s=0x1, buf=0xfffffe00, n=4294966784) at 
../../tools/libxutil/file_stream.c:77
#7  0x0804f499 in Conn_sxpr (conn=0xbffff900, sxpr=0xfffffe00) at 
iostream.h:114
#8  0x0804dd6c in xfr_vm_suspend (xend=0xbffff900, vmid=1) at xfrd.c:451
#9  0x40026524 in suspend_and_state () from /usr/lib/libxc.so.2.0
#10 0x40027c60 in xc_linux_save () from /usr/lib/libxc.so.2.0
#11 0x0804e9e4 in xen_domain_snd (xend=0xfffffe00, io=0xfffffe00, 
dom=4294966784, vmconfig=0xfffffe00 <Address 0xfffffe00 out of bounds>,
     vmconfig_n=-512, live=0, resource=-512) at xen_domain.c:39
#12 0x0804b79a in xfr_save (args=0x805d3b0, state=0xbffff820, 
xend=0xbffff900, file=0x805f9a8 "/tmp/foo") at xfrd.c:774
#13 0x0804c454 in xfrd_service (args=0x805d3b0, peersock=-512, peer_in=
       {sin_family = 2, sin_port = 12294, sin_addr = {s_addr = 
16777343}, sin_zero = "\000\000\000\000\000\000\000"}) at xfrd.c:950
#14 0x0804c8c8 in xfrd_accept (args=0xfffffe00, sock=2) at xfrd.c:1024
#15 0x0804c9b5 in xfrd_select (args=0x805d3b0, listen_sock=2) at 
xfrd.c:1054
#16 0x0804d1e8 in main (argc=1, argv=0xbffffe44) at xfrd.c:1210



-----
CTO @ Fotango Ltd
+447834716919
http://www.fotango.com/




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