[Qemu-devel] [BUG] Segfault on switching fda

[takis@lumumba.uhasselt.be (Panagiotis Issaris)]

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Hi,

Current CVS Qemu (of about 15 minutes ago) crashes when I run
qemu -snapshot -no-kqemu -fda a01
switch to the console and enter:
change fda a02

Leaving the "-snapshot" parameter out, makes the segfault go away.

The a01 and a02 files, are the bootdisks of the Atheos operating system
available here:
wget http://atheos.syllable-norden.info/download/0.3.7/base/atheos-0.3.7.boot.01
wget http://atheos.syllable-norden.info/download/0.3.7/base/atheos-0.3.7.boot.02

I've tried to get some more info using GDB.

With friendly regards,
Takis


takis@poseidon:/usr/local/src/qemu$ gdb ./i386-softmmu/qemu
GNU gdb 6.4-debian
Copyright 2005 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i486-linux-gnu"...Using host libthread_db library
"/lib/tls/i686/cmov/libthread_db.so.1".

(gdb) r -snapshot -no-kqemu -fda a01
Starting program: /usr/local/src/qemu/i386-softmmu/qemu -snapshot -no-kqemu -fda a01
[Thread debugging using libthread_db enabled]
[New Thread -1212549440 (LWP 24863)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1212549440 (LWP 24863)]
0x00000000 in ?? ()
(gdb) bt
#0  0x00000000 in ?? ()
#1  0x08052f0c in bdrv_read (bs=0x9b437e0, sector_num=-4631921361705500672, buf=0x9b61724 "æ nb_sectors=1) at /usr/local/src/qemu/block.c:429
#2  0x0808164a in fdctrl_transfer_handler (opaque=0x9b61708, nchan=2, dma_pos=0, dma_len=9216) at /usr/local/src/qemu/hw/fdc.c:990
#3  0x0807a024 in DMA_run () at /usr/local/src/qemu/hw/dma.c:343
#4  0x0805044f in main_loop_wait (timeout=0) at /usr/local/src/qemu/vl.c:4458
#5  0x080504e6 in main_loop () at /usr/local/src/qemu/vl.c:4532
#6  0x080517c3 in main (argc=5, argv=0xbfb84db4) at /usr/local/src/qemu/vl.c:5667
(gdb) up
#1  0x08052f0c in bdrv_read (bs=0x9b437e0, sector_num=-4631921361705500672, buf=0x9b61724 "æ nb_sectors=1) at /usr/local/src/qemu/block.c:429
429                 if (drv->bdrv_is_allocated(bs, sector_num, nb_sectors, &n))
{
(gdb) print *drv
$1 = {format_name = 0x8103c6b "raw", instance_size = 4, bdrv_probe = 0x8053542
<raw_probe>, bdrv_open = 0x8053548 <raw_open>, bdrv_read = 0x8053616 <raw_read>,
  bdrv_write = 0x8053679 <raw_write>, bdrv_close = 0x80536dc <raw_close>,
bdrv_create = 0x80536ee <raw_create>, bdrv_is_allocated = 0, bdrv_set_key = 0,
bdrv_make_empty = 0, next = 0x0}
(gdb) print *bs
$2 = {total_sectors = 2880, read_only = 0, inserted = 1, removable = 1, locked =
0, encrypted = 0, change_cb = 0x8080adc <fd_change_cb>, change_opaque =
0x9b61938, drv = 0x810d860,
  opaque = 0x9b42100, boot_sector_enabled = 0, boot_sector_data = '\0' <repeats
511 times>, filename = "a02\000/vl.F6Vgyj", '\0' <repeats 1009 times>,
  backing_file = "/usr/local/src/qemu/a01", '\0' <repeats 1000 times>,
is_temporary = 0, backing_hd = 0x9b44960, cyls = 0, heads = 0, secs = 0,
translation = 0, type = 2,
  device_name = "fda", '\0' <repeats 28 times>, next = 0x0}
(gdb)                                                                                  

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