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Re: [Qemu-devel] Re: gdbstub: packet reply is too long
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] Re: gdbstub: packet reply is too long |
Date: |
Sun, 04 Jan 2009 14:50:18 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
Jamie Lokier wrote:
> Jan Kiszka wrote:
>> You need CR0.PE to detect if you are in real or protected mode. And then
>> you need GDTR/LDTR to find the descriptor CS is pointing at, parsing it
>> to detect if you are running 16, 32 or 64 bit code (by default). Those
>> extensions would also be useful in order to decode memory addresses in
>> case descriptor.base != 0 (or if it's CS >> 4, ie. you are in real
>> mode).
>
> If you're going to decode segment descriptors (great idea, btw, and
> helpful for threaded code), it might be better to supply the CPU's
> internal segment state, if that's possible, instead of looking at the
> LDT/GDT in memory, since the CPU's state can differ from the memory
> version when the latter is written to.
Good point. I included this in an initial suggestion of an extended
register set, see [1]. Providing this information will likely remain
VM-business, but that doesn't mean we shouldn't use it when available.
Jan
[1] http://sourceware.org/ml/gdb/2009-01/msg00008.html
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