On Apr 1, 2013, at 11:03 AM, Tim Lewis <[email protected]> wrote:
> Andrew –
>
> You are a UEFI expert with tons of background knowledge. Newer engineers see
> an error like this and have no reasonable way to proceed. Try to dig up a FAQ
> on this?
This sounds like an issue in general. It would be nice to have an FAQ or
porting guide some place.
>
> The EDK2 environment should support normal C operations for all data types
> which are in the ABI. I can understand not supporting float intrinsics
> (floats aren’t actually a part of the ABI, even if they can be used in a
> module) But normal struct assignments, or UINT64 math?
>
The Math libs are probably a higher bar than a memcpy/memset. For ARM math libs
were required as one of the processors we targeted did not even have a divide
instruction. The biggest math lib issue for IA32.
> Now x86 appears handicapped in comparison to ARM on EDK2. Why allow this to
> persist?
Well there are really two issues: memcpy/memset vs. math. The math is only an
issue for IA32, while the memcpy/memset is more generic.
I'm not opposed to some one adding these kind of intrinsics to the
IA32/X64/IPF world, but these are the issues that I see:
1) It makes different version of the edk2 not compatible. The new code would
not be compatible with an older code base.
2) Some one has to add and maintain all these function. The math functions
being more complicated than the memcpy.
3) It is a possible extra per compiler porting work, but I have to say it turns
out that the intrinsics are more stable than we first thought since if the
compiler changes them it breaks standard libraries.
As you point out it might make it easier to port EDK code if we added the
memcpy, but there are still going to be porting issues. For example the scheme
for GIUD globals is very different between the EDK/edk2, so I think we need
some kind of FAQ to help folks out regardless of this memcpy issues.
Thanks,
Andrew
>
> Tim
>
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