I wrote:
> migrate "exec:dd of=STATEFILE"
> ... I was having trouble getting this to work (loading gave
> "Migration failed rc=233") and discovered that not all of the data
> was being saved, probably because of some buffering/pipe issues.
Actually, maybe that isn't the issue. I guess the migration data
might be different but still valid in both cases. The real place I'm
running into trouble is when trying to add migrate-to-file support
in libvirt. I'm having problems that I can't reproduce outside of
libvirt (ie. running kvm manually). For example I'm getting this
segfault, any ideas? It's almost as if migrate_write() is being
called after migrate_finish() ??
-jim
This is kvm-33:
Core was generated by `/usr/local/bin/qemu-system-x86_64 -M pc -m 256 -smp 1
-monitor pty -boot c -hda'.
Program terminated with signal 11, Segmentation fault.
#0 0x00002b1b0f786794 in memset () from /lib/libc.so.6
(gdb) bt full 8
#0 0x00002b1b0f786794 in memset () from /lib/libc.so.6
No symbol table info available.
#1 0x000000000047fd56 in kvm_get_dirty_pages_log_slot (slot=3, bitmap=0x0,
offset=0, len=24)
at /usr/local/src/kvm/kvm-33/qemu/qemu-kvm.c:1119
r = 3
i = 2620318256
j = 0
n = 3
c = 3 '\003'
page_number = 0
#2 0x000000000047fdf9 in kvm_update_dirty_pages_log () at
/usr/local/src/kvm/kvm-33/qemu/qemu-kvm.c:1152
r = 3
len = 0
#3 0x00000000004162c5 in migrate_write (opaque=0x0) at
/usr/local/src/kvm/kvm-33/qemu/migration.c:328
s = (MigrationState *) 0x2b58010
#4 0x000000000040c45d in main_loop_wait (timeout=2) at
/usr/local/src/kvm/kvm-33/qemu/vl.c:6236
pioh = (IOHandlerRecord **) 0x1
ioh = (IOHandlerRecord *) 0x2993f70
rfds = {fds_bits = {0 <repeats 16 times>}}
wfds = {fds_bits = {49152, 0 <repeats 15 times>}}
xfds = {fds_bits = {0 <repeats 16 times>}}
ret = 2
nfds = 15
tv = {tv_sec = 0, tv_usec = 0}
pe = (PollingEntry *) 0x2993f70
#5 0x000000000047f1c5 in kvm_main_loop_wait (env=0x296b670, timeout=10) at
/usr/local/src/kvm/kvm-33/qemu/qemu-kvm.c:604
No locals.
#6 0x000000000047f39f in kvm_main_loop_cpu (env=0x296b670) at
/usr/local/src/kvm/kvm-33/qemu/qemu-kvm.c:667
No locals.
#7 0x000000000040c6aa in main_loop () at
/usr/local/src/kvm/kvm-33/qemu/vl.c:6289
ret = 3
timeout = 0
env = (CPUX86State *) 0x0
(More stack frames follow...)
(gdb) p *(MigrationState *) 0x2b58010
$1 = {fd = 14, throttle_count = 533900, bps = 13271376, updated_pages = 0,
last_updated_pages = 11167, iteration = 1,
n_buffer = 9, l_buffer = 9, throttled = 0, has_error = 0x296b640,
buffer =
"\020\204�000\001\000\000\000\000\000\004\016\a\021\vv\fv\rv\016v\022\004\023\000\027
\0334\0344\0354\0364��\021)[EMAIL
PROTECTED]"\035\000��_\000\200\002�001\b\000\000\000a|G|\205|\b\004\000\000\000\000\000\000\000\000d\000\200\002�001\020\000�000�|G|�\020\006\005\v\006\005\005\000\000\000f\000\200\002�001\017\000�000�|G|�\020\006\005\n\005\005\005\000\001\017q\000\200\002�001\030\000�000\t}G|-}\030\006\b\020\b\b\b\000\000\000\\\000
\003X\002\b\000\000\000"..., addr = 0, timer = 0x2993f40,
opaque = 0x2993fc0, detach = 0, release = 0x4168c0 <cmd_release>,
rapid_writes = 0}
(gdb) p *((MigrationState *) 0x2b58010)->has_error
$2 = 0
I ran the following commands:
>
> (qemu) stop
> (qemu) migrate "exec:dd of=/tmp/jr1"
> (qemu) migrate "exec:cat > /tmp/jr2"
> (qemu) migrate "exec:dd bs=1 of=/tmp/jr3"
>
> And the file sizes:
>
> $ ls -al /tmp/jr[123]
> -rw-r--r-- 1 root root 86061424 2007-08-02 16:52 jr1
> -rw-r--r-- 1 root root 86220963 2007-08-02 16:53 jr2
> -rw-r--r-- 1 root root 86220963 2007-08-02 16:56 jr3
>
> Sometimes the "cat" gives a filesize similar to "dd", depending on
> image size. Only "dd bs=1" appears to always give me all of the data.
> Sometimes the truncated images work fine for resume, other times they
> cause a "migration failed".
>
> I haven't had a chance yet to dig too deep in the source to find the
> cause. I haven't seeen if this truncation also happens over TCP.
>
> This was tested with kvm-28 modules and both kvm-28 and kvm-33
> userspace. Has anyone else seen this?
>
> -jim
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