Re: [Xen-devel] [PATCH] x86emul: correct LFS et al handling for 64-bit mode

[Jan Beulich <jbeulich@xxxxxxxx>]

On 11.12.2019 21:57, Andrew Cooper wrote:
> On 11/12/2019 09:28, Jan Beulich wrote:
>> AMD and friends explicitly specify that 64-bit operands aren't possible
>> for these insns. Nevertheless REX.W isn't fully ignored: It still
>> cancels a possible operand size override (0x66). Intel otoh explicitly
>> provides for 64-bit operands on the respective insn page of the SDM.
>>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> It is definitely more than just these.  Near jumps have per-vendor
> behaviour on how long the instruction is, whereas far jump/calls are in
> the same category as these by the looks of things.

But you don't expect me to fold all of these into one patch, do
you? We have _some_ vendor dependent behavior already, and I'm
slowly adding to it. Our far call/jmp support is rather
incomplete in other ways anyway. (As an aside, I'm trying to do
the binutils side of some of these before wanting to do the
emulator parts. I'm only about to get to the far call/jmp issues
there, as reported by you in bug 24546.)

I'd appreciate if you could clarify what exactly your reply
means for the patch at hand.

Jan

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