Re: year old problem
Andi Kleen (ak@muc.de)
Tue, 16 Nov 1999 00:47:27 +0100
On Mon, Nov 15, 1999 at 11:36:31PM +0100, Eric Pouech wrote:
> well, it seems to me that the code in __switch_to (loaddebug macro) *restores*
> the DBi registers (from the tss in memory to the i386) while switching to 'next'
> process
>
> my issue is that the i386 value of DR6 (status => which debug registers
> which (may) have triggered a trap) are never (I should say no longer)
> stored in tss as they used to be (and therefore never accessible with ptrace)
>
> in 2.0.x series, they were stored in tss while entering the TRAP handler
> and it's no longer the case.
Point taken. It seems to be a bug.
For DR0-DR3/DR7 it doesn't make sense to save them all the time (because they
can be set by ptrace, even by the program), but DR4-6 should be saved.
-Andi
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