[patch] x86: fix ESP corruption CPU bug

[Brian Gerst]

linux-os wrote:
> On Mon, 14 Mar 2005, Jakob Eriksson wrote:
> 
>> Andi Kleen wrote:
>>
>>> Stas Sergeev <stsp at aknet.ru> writes:
>>>
>>>>> Another way of saying the same thing: I absolutely hate seeing
>>>>> patches that fix some theoretical issue that no Linux apps will ever
>>>>> care about.
>>>>>
>>>> No, it is not theoretical, but it is mainly
>>>> about a DOS games and an MS linker, as for
>>>> me. The things I'd like to get working, but
>>>> the ones you may not care too much about:)
>>>> The particular game I want to get working,
>>>> is "Master of Orion 2" for DOS.
>>>>
>>>
>>> How about you just run it in dosbox instead of dosemu ?
>>>
>>
>> Yes, that's a solution of course, but it is a bit like saying why
>> not use Open Office instead of MS Word.
>>
>> A long term goal of wine is to support DOS apps to. Of course
>> it's not a priority, but it's there.
>>
>> regards,
>> Jakob
>>
> 
> Can you tell me how the invisible high-word (invisible in VM-86, and
> in real mode) could possibly harm something running in VM-86 or
> read-mode ???  I don't even think it's a BUG. If the transition
> into and out of VM-86 doesn't handle the fact that the high-word
> of the stack hasn't been used in VM-86, then that piece of code
> is bad (the SP isn't even the same stack, BTW).

Because even in 16-bit mode (real, vm86 or 16-bit protected) you can use 
32-bit instructions, with an operand and/or address size override 
prefix.  Of course this only works on 386 or later.

--
				Brian Gerst