Re: [PATCH v2] eal_common_cpuflags: Fix %rbx corruption, and simplify the code

[Thomas Monjalon <thomas.monjalon-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>]

21/03/2014 13:48, Neil Horman:
> On Fri, Mar 21, 2014 at 08:03:34AM -0700, H. Peter Anvin wrote:
> > On 03/21/2014 07:49 AM, Neil Horman wrote:
> > > From: "H. Peter Anvin" <hpa-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> > > 
> > > Neil Horman reported that on x86-64 the upper half of %rbx would get
> > > clobbered when the code was compiled PIC or PIE, because the
> > > i386-specific code to preserve %ebx was incorrectly compiled.
> > > 
> > > However, the code is really way more complex than it needs to be.  For
> > > one thing, the CPUID instruction only needs %eax (leaf) and %ecx
> > > (subleaf) as parameters, and since we are testing for bits, we might
> > > as well list the bits explicitly.  Furthermore, we can use an array
> > > rather than doing a switch statement inside a structure.
> > > 
> > > Reported-by: Neil Horman <nhorman-2XuSBdqkA4R54TAoqtyWWQ@public.gmane.org>
> > > Signed-off-by: H. Peter Anvin <hpa-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> > > Tested-by: Neil Horman <nhorman-2XuSBdqkA4R54TAoqtyWWQ@public.gmane.org>
> > 
> > Thank you for dealing with this!
> > 
> > On the subject of my other email... are C99 initializers acceptable in
> > dpdk?  If so, I think making that change, too, would be a good idea.
> 
> I'll have to defer this to others, I'm not sure what the accepted
> initalization method is.  I'm guessing their fine, as both icc and gcc
> allow them and those are the supported compilers for dpdk, but I'd like to
> hear someone in the maintainership comment.

Yes, DPDK use C99 syntax.
Feel free to use it in a v3 :)

-- 
Thomas