[OpenAFS] Re: modload failing, Sol10 SPARC, 1.4.14

Derrick Brashear shadow@gmail.com
Tue, 31 May 2011 18:44:24 -0400

On Tue, May 31, 2011 at 2:13 PM, Andrew Deason <adeason@sinenomine.net> wro=
> On Tue, 31 May 2011 12:14:31 -0500
> Andrew Deason <adeason@sinenomine.net> wrote:
>> Or I can just find it by commenting stuff out and seeing when the
>> _memset ref goes away. It appears to be this loop that's causing it, in
>> afs_RebuildDynroot lines 378/379:
>> =A0 =A0 for (i =3D 0; i < NHASHENT; i++)
>> =A0 =A0 =A0 =A0 =A0 =A0 dirHeader->hashTable[i] =3D 0;
>> which makes sense; that's pretty easily optimizable into a memset.

or, for now, just replace that with
memset(dirHeader->hashTable, 0, NHASHENT*(unsigned short));

and move along?

>> I'll get a simpler demonstration together to submit to Oracle.
> Also, Jeff, if you want a quick workaround, you can change -O to -O2 or
> just leave out the -O option. I think changing the value of KERN_OPTMZ
> in src/cf/osconf.m4 should be enough...
> And now I'm not completely sure if this is a bug or if we're just
> missing the magic incantation to make this not happen. A simple test
> case:
> void
> foo(short *arr)
> {
> =A0 =A0int i;
> =A0 =A0for (i =3D 0; i < 256; i++)
> =A0 =A0 =A0 =A0arr[i] =3D 0;
> }
> If you compile with 'cc foo.c -c -o foo.o -O3', you get a reference to
> _memset. If you compile with -O2 or below, you don't. Passing
> -xbuiltin=3D%none, any of the -xno*lib or -xc99 etc options don't seem to
> change anything. With older versions of Sun/Solaris Studio, it never
> seems to call _memset.
> The Oracle documentation on this is puzzling to me:
> <http://download.oracle.com/docs/cd/E19205-01/821-1384/gjzku/index.html>
> It says "The following table lists runtime support functions that may be
> called in code compiled to run in the Solaris kernel, as a result of
> source code translation by the C compiler." the table includes _memset,
> _memcpy, et al. Then it says
> "Note that some versions of the kernel do not provide _memmove(),
> _memcpy(), or _memset(), but do provide kernel mode analogues of the
> user mode routines memmove(), memcpy(), and memset()."
> But it doesn't say how to avoid it. I'm not sure if there's a compiler
> flag we're missing here, or if it's not supported to use -O3 for kernel
> modules, or... ? Or it's just a bug. It's also interesting that this
> doesn't happen on amd64, though I assume that's just because it uses
> different arch-specific optimizations.
> I don't know, should I just try to file a bug anyway, or should we try
> to get someone with a support contract to say something?
> --
> Andrew Deason
> adeason@sinenomine.net
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