[Mesa-dev] [PATCH] meson: Allow use of ASM for x86 host with x86_64 build machine

[Dylan Baker]

Quoting Eric Anholt (2018-06-08 09:10:35)
> Dylan Baker <dylan at pnwbakers.com> writes:
> 
> > [ Unknown signature status ]
> > Quoting Eric Anholt (2018-06-07 14:34:02)
> >> Dylan Baker <dylan at pnwbakers.com> writes:
> >> 
> >> > The reason we restrict the use of ASM when cross compiling is that there
> >> > is a C based generator (mtypes) that must be run as part of the build
> >> > process, and it must be built for the host architecture. In the case of
> >> > an x86 host and an x86_64 build machine this is possible as long as the
> >> > host and build OSes are the same (ie, not Windows -> Linux).
> >> >
> >> > This also makes the commit message a bit more generic than it previously
> >> > was.
> >> 
> >> Given that the igt meson build has been running some of my
> >> cross-compiled arm binaries under qemu during its build process, I
> >> actually don't think we need to restrict running matypes compiled for
> >> the host.
> >
> > I have a todo about that actually. Really the only cases we need to restrict are
> > x86 -> x86_64 and !x86* -> x86*; (since only x86* uses gen_matypes). I just
> > haven't had time to test using an exe_wrapper for that purpose, and meson
> > doesn't enforce that you have an exe_wrapper, so we still need to disable the
> > assembly if you don't have one.
> 
> I would be on board with just requiring an exe_wrapper for cross builds
> on archs with asm -- why would you want to build Mesa without asm?

Matt tells me that people interested in system hardening don't use it, but
that's pretty niche.

I looked at it a little more, the only place it actually matters is for x86*, no
other architecture makes use of gen_matypes thing. I wonder if we can replace
gen_matypes with something that doesn't have to be compiled?

Dylan
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