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Date: Tue, 18 Nov 2008 15:45:26 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH v5 18/18] gdbstub: x86: Switch 64/32 bit
	registers dynamically
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To: qemu-devel@nongnu.org
Cc: Jan Kiszka <jan.kiszka@siemens.com>, Paul Brook <paul@codesourcery.com>

Anthony Liguori wrote:
> Jan Kiszka wrote:
>> Commit 5459 broke gdbstub's dynamic register set switching between
>> x86-64 and i386. That prevents setting the correct architecture in gdb
>> when debugging 32 or 16-bit code in a 64-bit emulator. This patch
>> reintroduces the feature over previous refactorings.
>>   
>
> How does this interact with SMP?  If you have one VCPU in 32-bit mode 
> and another in 64-bit mode, won't that confuse GDB?

After talking to Paul in IRC, it seems that GDB is going to make 
assumptions that all threads share an address space and potentially 
cache memory accesses or at least be sloppy with how it does memory 
accesses.

I think this is a pretty strong argument for using fork instead of 
threads.  I would think you should be able to provoke this pretty easily 
with an SMP guest.

Regards,

Anthony Liguori

> Regards,
>
> Anthony Liguori
>
>
>>
>>   
>