Re: [Qemu-devel] Re: [PATCH v5 18/18] gdbstub: x86: Switch 64/32 bit registers dynamically

[Jan Kiszka <jan.kiszka@web.de>]

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Paul Brook wrote:
>> The best approach, definitely, would be to teach GDB how to switch the
>> disassembler mode depending on the thread's (or VCPUs) state. But so
>> there is neither a mechanism in GDB for this, nor is GDB even aware of
>> the x86 modes (no tracking of privileged registers). We have some
>> preliminary patches for this, but they are still far away from GDB
>> mainline.
> 
> I'm pretty sure all the infrastructure is there. gdb is able to natively debug 
> 32-bit binaries on a 64-bit host and is able to switch disassembler modes for 
> ARM vs. Thumb.

How is it done on ARM? Maybe that will provide the right pointer for x86.

For fun I recently tried to debug a 32-bit binary on a 64-bit host via
gdbserver - the fun ended as quickly as with qemu. The only way for
switching disassembly mode on x86 that I found is via set arch, and that
switching the register packet format as well.

Jan


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