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Date: Thu, 7 Oct 2010 12:27:47 +0400 (MSD)
From: malc <av1474@comtv.ru>
Subject: Re: [Qemu-devel] Re: [PATCH 09/11] i386: avoid a write only variable
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Blue Swirl <blauwirbel@gmail.com>, qemu-devel <qemu-devel@nongnu.org>

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On Thu, 7 Oct 2010, Paolo Bonzini wrote:

> On 10/06/2010 11:34 PM, Blue Swirl wrote:
> > Compiling with GCC 4.6.0 20100925 produced warnings:
> > /src/qemu/target-i386/op_helper.c: In function 'switch_tss':
> > /src/qemu/target-i386/op_helper.c:283:53: error: variable 'new_trap'
> > set but not used [-Werror=unused-but-set-variable]
> > 
> > Fix by deleting the variable.
> 
> Again, this warning tells us the emulation is incorrect, so it's wrong to
> remove it.
> 

http://support.amd.com/us/Processor_TechDocs/24593.pdf 

12.2.5
T (Trap) Bit--■Bit 0 of byte 64h, static field. This bit, when set to1,
causes a debug exception (#DB) to occur on a task switch. See "Beakpoint
Instruction (INT3)" page 340 for additional information.

current code never checks and never traps, which is indeed not correct.

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