This is the mail archive of the libc-ports@sources.redhat.com mailing list for the libc-ports project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH v2] ARM: Use different linker path for hardfloat ABI


On 05/01/2012 10:52 AM, Richard Earnshaw wrote:
On 30/04/12 22:47, Michael Hope wrote:
On 1 May 2012 03:24, Richard Earnshaw<rearnsha@arm.com> wrote:
On 27/04/12 00:27, Michael Hope wrote:
On 27 April 2012 08:20, Carlos O'Donell<carlos@systemhalted.org> wrote:
On Mon, Apr 23, 2012 at 5:36 PM, Michael Hope<michael.hope@linaro.org> wrote:
2012-04-24  Michael Hope<michael.hope@linaro.org>
            Richard Earnshaw<rearnsha@arm.com>

        * config/arm/linux-eabi.h (GLIBC_DYNAMIC_LINKER_SOFT_FLOAT): Define.
        (GLIBC_DYNAMIC_LINKER_HARD_FLOAT): Define.
        (GLIBC_DYNAMIC_LINKER_DEFAULT): Define.
        (GLIBC_DYNAMIC_LINKER): Redefine to use the hard float path.

diff --git a/gcc/config/arm/linux-eabi.h b/gcc/config/arm/linux-eabi.h
index 80bd825..2ace6f0 100644
--- a/gcc/config/arm/linux-eabi.h
+++ b/gcc/config/arm/linux-eabi.h
@@ -62,7 +62,17 @@
  /* Use ld-linux.so.3 so that it will be possible to run "classic"
    GNU/Linux binaries on an EABI system.  */
  #undef  GLIBC_DYNAMIC_LINKER
-#define GLIBC_DYNAMIC_LINKER "/lib/ld-linux.so.3"
+#define GLIBC_DYNAMIC_LINKER_SOFT_FLOAT "/lib/ld-linux.so.3"
+#define GLIBC_DYNAMIC_LINKER_HARD_FLOAT "/lib/ld-linux-armhf.so.3"
+#if TARGET_DEFAULT_FLOAT_ABI == ARM_FLOAT_ABI_HARD
+#define GLIBC_DYNAMIC_LINKER_DEFAULT GLIBC_DYNAMIC_LINKER_HARD_FLOAT
+#else
+#define GLIBC_DYNAMIC_LINKER_DEFAULT GLIBC_DYNAMIC_LINKER_SOFT_FLOAT
+#endif
+#define GLIBC_DYNAMIC_LINKER \
+   "%{mfloat-abi=hard:" GLIBC_DYNAMIC_LINKER_HARD_FLOAT "} \
+    %{mfloat-abi=soft*:" GLIBC_DYNAMIC_LINKER_SOFT_FLOAT "} \
+    %{!mfloat-abi=*:" GLIBC_DYNAMIC_LINKER_DEFAULT "}"

  /* At this point, bpabi.h will have clobbered LINK_SPEC.  We want to
    use the GNU/Linux version, not the generic BPABI version.  */

This patch is broken. Please fix this.


You can't use a named enumeration in cpp equality.

The type ARM_FLOAT_ABI_HARD is a named enumeration and evaluates to 0
as an unknown identifier.

Therefore "#if TARGET_DEFAULT_FLOAT_ABI == ARM_FLOAT_ABI_HARD"
evaluates to "#if 0 == 0" and is always true.

Watch out that "#define ARM_FLOAT_ABI_HARD ARM_FLOAT_ABI_HARD" for
such enums is not conforming C99/C11.

I suggest you define the types as macros and then set the named enum
to those values, then use the macros in the header equality checks.

e.g.
#define VAL1 0 then enum FOO { RVAL1 = VAL1, ... }

Look at arm.h for the enum definition.

I've looked further into this and I think the original pre-#if version is correct.

The float ABI comes from these places:
  * The -mfloat-abi= command line argument, else
  * The --with-float= configure time argument, else
  * TARGET_DEFAULT_FLOAT_ABI from linux-eabi.h

In the first case the ABI is explicit.  In the second
OPTION_DEFAULT_SPECS turns the configure time argument into an explict
-mfloat-abi=.

The patch below covers all cases, keeps the logic in the spec file,
and adds a comment linking the two #defines.

Tested by building with no configure flags, --wtih-float=softfp,
--with-float=hard, and then running with all combinations of
{,-mfloat-abi=softfp,-mfloat-abi=hard} {,-mglibc,-muclibc,-mbionic}.

OK?

-- Michael

2012-04-27 Michael Hope<michael.hope@linaro.org>

       * config/arm/linux-eabi.h (GLIBC_DYNAMIC_LINKER): Pick the loader
       using a spec rule.


Michael,


can you try this patch please.  It should make it possible to then
create linux-eabihf.h containing just

#undef TARGET_DEFAULT_FLOAT_ABI
#define TARGET_DEFAULT_FLOAT_ABI ARM_FLOAT_ABI_HARD
#undef GLIBC_DYNAMIC_LINKER_DEFAULT
#define GLIBC_DYNAMIC_LINKER_DEFAULT GLIBC_DYNAMIC_LINKER_HARD_FLOAT

Which is not quite as simple as leaving out the second re-define, but
pretty close.

Hi Richard. Your patch tests just fine. I like it. You could change the spec rule to the newer if-elseif-else form but that's a nit.

-- Michael


Great, thanks! I've committed it as is.

I suggest to add this also to the gcc 4.7 branch. Richard (Earnshaw), could you do take care of this, please?


Thanks,
Andreas
--
 Andreas Jaeger aj@{suse.com,opensuse.org} Twitter/Identica: jaegerandi
  SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
   GF: Jeff Hawn,Jennifer Guild,Felix Imendörffer,HRB16746 (AG Nürnberg)
    GPG fingerprint = 93A3 365E CE47 B889 DF7F  FED1 389A 563C C272 A126


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]