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Re: [Qemu-devel] Re: [PATCH] i386 debugging stubs: Consider segment base
Re: [Qemu-devel] Re: [PATCH] i386 debugging stubs: Consider segment bases
Sat, 25 Sep 2010 01:35:39 -0700
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Thanks for the response. I agree the patch is a workaround, but it is a
useful workaround, and I'd still argue for including it.
The patch doesn't *require* that CS.base == DS.base. Breakpoints
correctly and exclusively use CS.base. However, any memory examination
uses DS.base, and you're right that the user might "want" to examine
some other segment. A GDB fix would involve changing the gdb remote
protocol as well as GDB itself and the GDB user interface. Google says
you've been thinking about that for a while now -- is it going well?
For the time being, you should be able to workaround the gdb limitation
by setting two breakpoints: one on the linear address and another one on
the CS offset. Not nice, but used to work for us.
I don't mind the double-breakpoint as much, but memory examination would
still be broken, yes?
I don't understand the comment about "prevents setting breakpoints on
inactive segments." The code for setting breakpoints has not changed.
Do you think the patch would actually make debugging WORSE on any OS?
Or have any other undesirable effects, or make it harder to DTRT when
GDB is ready? It seems safe & useful to me; & it's 2 LOC!