[fpc-devel] cross copiling x86_64 to i386 ?

Hans-Peter Diettrich DrDiettrich1 at aol.com
Fri Aug 31 04:03:24 CEST 2012

Jonas Maebe schrieb:
> On 30 Aug 2012, at 23:50, Dimitrios Chr. Ioannidis wrote:

>> "The MMX and floating-point stack registers (MM0-MM7/ST0-ST7) are
>> preserved across context switches. There is no explicit calling
>> convention for these registers. The use of these registers is
>> strictly prohibited in kernel mode code."
> That is unrelated to whether or not their use is deprecated. If they
> weren't preserved across context switches, virtually no 32 bit
> Windows program would still work on 64 bit Windows.

Thanks for the detailed information.

One thing seems to be clear: the instructions to save the CPU state have 
to be used in context switches. Now it depends on the available 
instructions, whether the FPU state is always included; this again may 
be different for the 32 and 64 bit instructions or drivers (dunno).


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