RFC: Document GNU_PROPERTY_X86_XXX

[H.J. Lu]

On Fri, Aug 10, 2018 at 3:40 PM, H.J. Lu <hjl....@gmail.com> wrote:
> On Fri, Aug 10, 2018 at 3:23 PM, Cary Coutant <ccou...@gmail.com> wrote:
>>> Add GNU_PROPERTY_X86_FEATURE_2_USED and GNU_PROPERTY_X86_FEATURE_2_NEEDED
>>> to NT_GNU_PROPERTY_TYPE_0 note to mark processor features used and
>>> required in x86 ELF binaries. These 2 new properties can be used together
>>> GNU_PROPERTY_X86_ISA_1_USED and GNU_PROPERTY_X86_ISA_1_NEEDED to describe
>>> instruction sets and processor features contained in x86 ELF binaries.
>>> ...
>>> Any comments?
>>
>> Do you expect the FEATURE_2_USED property to be treated the same as
>> the ISA_USED property -- namely, that if any object is missing the
>> property (or has all zeroes), the output should not have the property?
>
> Yes.
>
>> It seems to me that you should generalize the types of merging
>> operations that a linker is expected to perform, and encode that as
>> part of the property, so that the linker doesn't need to special-case
>> the handling of every new property.
>
> It sounds a good idea. We have
>
> #define GNU_PROPERTY_X86_ISA_1_USED 0xc0000000
>
> What is the best way to add a generic type marker to include
> it?
>

Here is a proposal to add GNU_PROPERTY_X86_XXX. GNU_PROPERTY_X86_ISA_1_USED
and GNU_PROPERTY_X86_ISA_1_NEEDED values are different from existing
values. The
original values are left unused. Any comments?


--
H.J.

[H.J. Lu]

Here is the update x86-64 psABI pdf file:

https://github.com/hjl-tools/x86-psABI/wiki/x86-64-psABI-property.pdf

Binutils patches are posted at

https://sourceware.org/ml/binutils/2018-08/msg00321.html

I will check them into binutils master banch this Friday.


--
H.J.