[flashrom] [PATCH] Fix compilation on SunOS.

[Stefan Tauner]

On Sun, 13 Mar 2016 08:38:25 +0100
Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net> wrote:

> On 13.03.2016 00:57, Stefan Tauner wrote:
> > On Sun, 13 Mar 2016 00:26:41 +0100
> > Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net> wrote:
> >
> >> On 13.03.2016 00:05, Stefan Tauner wrote:
> >>> This came up when I was testing if building on SunOS still works
> >>> on the buildbot's instance of OmniOS r151014 which is based on illumos.
> >>>
> >>> The fix is
> >>>  - to link against libnsl
> >>>  - a small C type fix in ich_descriptor_tool
> >>>
> >>> Signed-off-by: Stefan Tauner <stefan.tauner at alumni.tuwien.ac.at>
> >>> Acked-by: Stefan Tauner <stefan.tauner at alumni.tuwien.ac.at>
> >>>  
> >>> diff --git a/util/ich_descriptors_tool/ich_descriptors_tool.c b/util/ich_descriptors_tool/ich_descriptors_tool.c
> >>> index c3d9ba1..ad3b6f0 100644
> >>> --- a/util/ich_descriptors_tool/ich_descriptors_tool.c
> >>> +++ b/util/ich_descriptors_tool/ich_descriptors_tool.c
> >>> @@ -170,7 +170,7 @@ int main(int argc, char *argv[])
> >>>  		usage(argv, "Seeking to the end of the file failed");
> >>>  
> >>>  #ifdef HAVE_MMAP
> >>> -	buf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
> >>> +	buf = (uint32_t *)mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
> >> The compiler may require that to stop complaining, but AFAICS there is a
> >> real bug behind this. buf is sometimes casted to uint8_t *, and unless
> >> I'm too sleepy already, this buffer violates the strict aliasing rules.
> >> We can solve this with -fno-strict-aliasing, or fix the code. With a
> >> code fix, in theory the problem should go away.
> > While this is true it does not make much sense to try to fix it:
> >  - all accesses are read-only. The compiler can re-order as much as it
> >    wants, we won't get wrong results. No compiler writers however mean
> >    will make this explode. And that's the only potential problem with
> >    aliasing.
> >  - ich_descriptor.c intentionally uses undefined behavior by writing to
> >    some struct members and reading it through others to spare us from
> >    bit-shifting/masking. That was discussed at length back when I added
> >    it and since we use the code on x86 only it is fine.
> 
> Ah right.
> Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>

Thanks, r1950.
-- 
Kind regards/Mit freundlichen Grüßen, Stefan Tauner