[Qemu-devel] Dump registers?

[Pierre-Alexandre Meyer <pierre@mouraf.org>]

Good morning,

  I am developing an application at the bootloader level that
eventually jumps into protected mode. My testing is done using the
qemu Ubuntu Intrepid build (0.9.1).

Doing something like

  qemu -M pc -hda foo.vmdk -m 1000 -no-kqemu -boot c -S -s

and connecting gdb works great... until the application jumps into
protected mode when gdb becomes really confused.

Setting a break point at the first function after protected mode doesn't
work.

With no break points, if I SIGINT the program after the jump, gdb is confused:

   Backtrace stopped: previous frame inner to this frame (corrupt stack?)

This makes sense I suppose since the segment registers were changed
since gdb was started. I have then access to the registers but I am not sure
how accurate they are.

Is there a way to ask qemu to dump these registers (as well as the
descriptor tables)? I saw once a dump like:

  qemu: fatal: triple fault
  EAX=6000004d EBX=00000914 ECX=00000000 EDX=000028a3
  ESI=00000000 EDI=00005443 EBP=00000028 ESP=00007c48
  EIP=00002800 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
  ES =0010 00000000 ffffffff 008f9300
  CS =0008 00000000 0000ffff 00009b00
  SS =0038 00000000 0000ffff 00009300
  DS =0010 00000000 ffffffff 008f9300
  FS =0018 00000000 0000ffff 00009300
  GS =0018 00000000 0000ffff 00009300
  LDT=0000 00000000 00000000 00008000
  TR =0030 0000285c 00000067 00008900
  GDT=     000028c4 0000003f
  IDT=     00000000 0000ffff
  CR0=60000011 CR2=00000000 CR3=00000000 CR4=00000000
  CCS=6000004d CCD=600000d0 CCO=ADDB
  FCW=037f FSW=0000 [ST=0] FTW=00 MXCSR=00001f80
  FPR0=0000000000000000 0000 FPR1=0000000000000000 0000
  FPR2=0000000000000000 0000 FPR3=0000000000000000 0000
  FPR4=0000000000000000 0000 FPR5=0000000000000000 0000
  FPR6=0000000000000000 0000 FPR7=0000000000000000 0000
  XMM00=00000000000000000000000000000000
  XMM01=00000000000000000000000000000000
  XMM02=00000000000000000000000000000000
  XMM03=00000000000000000000000000000000
  XMM04=00000000000000000000000000000000
  XMM05=00000000000000000000000000000000
  XMM06=00000000000000000000000000000000
  XMM07=00000000000000000000000000000000

This is exactly what I am looking for. Any idea if I can force such a
dump on demand and/or fix gdb?

Thank you.

(Please CC: me when replying, since I am not on the list)

-- 
Pierre-Alexandre Meyer