[Qemu-devel] question about qemu-generated vmcore

[Qemu-devel] question about qemu-generated vmcore

[Wen Congyang]

Hi all.

As you know, I am implementing a new, dedicated memory dump mechanism.
crash cannot get phys_base, because the guest may be in the kdump kernel.

As Dave and hatayama suggested, I want to put extra CPU's information
in PT_NOTE.

For example:
$ readelf -n vmcore

Notes at offset 0x000001c8 with length 0x00000838:
  Owner         Data size       Description
  CORE          0x00000150      NT_PRSTATUS (prstatus structure)
  CORE          0x00000150      NT_PRSTATUS (prstatus structure)
  QEMU          0x00000557      Unknown note type: (0x00000000)
  QEMU          0x00000557      Unknown note type: (0x00000000)

We put all CPU's information in the QEMU note. But I am not sure
which informatin we should put in it. I think the following thing
should be put in QEMU note:
standard register: rax, rbx, rcx, rdx, rsi, rdi, rsp, rbp, r8,
                   r9, r10, r11, r12, r13, r14, r15
segments: cs, ds, es, fs, gs, ss, ldt, tr, gdt, idt
control register: cr0-cr5
other register: rip, rflags

Hatayama suggested appending versions at the head of CPU's information.
I agree with it, because CPU may have more registers in the future.

Any other register or other information should be included in QEMU notes?
Any suggestion is welcome.

Thanks
Wen Congyang