[PATCH v2 02/10] Add Aarch64 SVE Linux headers

[Simon Marchi]

On 2018-06-12 10:43, Pedro Alves wrote:
> What's "this" ?

 From what I understand, "this" is the suggestion I made in my previous 
mail, require the user to build against the headers of a recent kernel 
(that provide the SVE macros), and not provide a stop-gap copy in the 
GDB tree.  It would break the buildbot, because they have an old kernel 
that doesn't provide the SVE macros the GDB code uses (e.g. 
SVE_PT_REGS_OFFSET).

> How about we add a configure check to check if the system headers 
> support
> the needed SVE bits, and guard the native gdb SVE bits with
> HAVE_AARCH64_SVE or something like that?

I think that would be a good compromise.  By default, building on a 
machine with an older kernel would exclude SVE support.  But it would be 
possible to add it by pointing to the headers of a recent kernel.  So 
when building on a machine with an older kernel...

- ... without any special flags, you don't get SVE support.
- ... with just --enable-sve, you get a configure error.
- ... with --enable-sve and CFLAGS/CXXFLAGS pointing to headers of a 
kernel w/ SVE macros, you get SVE support.

Does that make sense?

Simon