Re: [PATCH 2/2] Detect 64-bit-ness in PowerPC Book III-E

Ulrich Weigand
2015-01-13T17:00:56Z

Yao Qi wrote:

> gdb:
>
> 2015-01-11 Yao Qi <yao@codesourcery.com>
>
> * Makefile.in (ppc-linux.o): New rule.
> * config/powerpc/ppc64-linux.mh (NATDEPFILES): Add ppc-linux.o.
> * nat/ppc-linux.h [__powerpc64__] (ppc64_64bit_inferior_p):
> Declare.
> * nat/ppc-linux.c: New file.
> * ppc-linux-nat.c (ppc_linux_target_wordsize) [__powerpc64__]:
> Call ppc64_64bit_inferior_p.
>
> gdb/gdbserver:
>
> 2015-01-11 Yao Qi <yao@codesourcery.com>
>
> * Makefile.in (SFILES): Add nat/ppc-linux.c.
> (ppc-linux.o): New rule.
> * configure.srv (powerpc*-*-linux*): Add ppc-linux.o.
> * linux-ppc-low.c (ppc_arch_setup) [__powerpc64__]: Call
> ppc64_64bit_inferior_p

This is OK in principle, however:

> +static void
> +ppc64_host_hwcap (unsigned long *valp)
> +{
> + unsigned char data[2 * 8];
> + FILE *f = fopen ("/proc/self/auxv", "r");
> +
> + if (f == NULL)
> + return;
> +
> + while (fread (data, sizeof (data), 1, f) > 0)
> + {
> + unsigned long *data_p = (unsigned long *) data;
> +
> + if (data_p[0] == AT_HWCAP)
> + {
> + *valp = data_p[1];
> + break;
> + }
> + }
> +
> + fclose (f);
> +}

All this can be done using "getauxval (AT_HWCAP)", which is faster and works
even if /proc is not mounted. However, getauxval was only introduced with
glibc 2.16, so we'll probably still need the fallback ...

Bye,
Ulrich

--
Dr. Ulrich Weigand
GNU/Linux compilers and toolchain
Ulrich.Weigand@de.ibm.com