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

Simon Marchi
2018-06-12T15:06:22Z

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