[Buildroot] [PATCH] package/uclibc: enable FENV support

[Buildroot] [PATCH] package/uclibc: enable FENV support

[Waldemar Brodkorb]

Enable FENV support unconditionally when a hard-float toolchain is in use.
Useful for packages as quickjs and chawan.
Adds 24kb to the C library on aarch64.

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
---
 package/uclibc/uclibc.mk | 1 +
 1 file changed, 1 insertion(+)

diff --git a/package/uclibc/uclibc.mk b/package/uclibc/uclibc.mk
index 0cee106014..c19328e87a 100644
--- a/package/uclibc/uclibc.mk
+++ b/package/uclibc/uclibc.mk
@@ -286,6 +286,7 @@ else
 define UCLIBC_FLOAT_CONFIG
 	$(call KCONFIG_ENABLE_OPT,UCLIBC_HAS_FPU)
 	$(call KCONFIG_ENABLE_OPT,UCLIBC_HAS_FLOATS)
+	$(call KCONFIG_ENABLE_OPT,UCLIBC_HAS_FENV)
 endef
 endif
 
-- 
2.47.3

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Re: [Buildroot] [PATCH] package/uclibc: enable FENV support

[Julien Olivain via buildroot]

On 16/08/2026 11:24, Waldemar Brodkorb wrote:
> Enable FENV support unconditionally when a hard-float toolchain is in 
> use.
> Useful for packages as quickjs and chawan.
> Adds 24kb to the C library on aarch64.
> 
> Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>

Applied to master, thanks.
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Re: [Buildroot] [PATCH] package/uclibc: enable FENV support

[Thomas Petazzoni via buildroot]

Hello,

On Sun, Aug 16, 2026 at 11:24:40AM +0200, Waldemar Brodkorb wrote:
> Enable FENV support unconditionally when a hard-float toolchain is in use.
> Useful for packages as quickjs and chawan.
> Adds 24kb to the C library on aarch64.
> 
> Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>

I am not 100% sure, but this seems to have broken the build of gcc
14.4.0 on x86 32-bit:

  https://autobuild.buildroot.net/?reason=host-gcc-final-14.4.0&libc=uclibc

Even though we've had gcc 14.4.0 for a while, this only started
happening on August 16, first bad commit being 9ac19958, which is
shortly after this fenv support in uClibc was enabled.

And the build failure clearly connects to fenv:

In file included from ../../../libquadmath/math/x2y2m1q.c:19:
../../../libquadmath/quadmath-imp.h:310:8: error: redefinition of 'struct rm_ctx'
  310 | struct rm_ctx
      |        ^~~~~~
In file included from ../../../libquadmath/quadmath-imp.h:32:
/home/autobuild/autobuild/instance-16/output-1/host/i686-buildroot-linux-uclibc/sysroot/usr/include/fenv.h:137:8: note: originally defined here
  137 | struct rm_ctx
      |        ^~~~~~

Could you have a look into this?

Thanks!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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Re: [Buildroot] [PATCH] package/uclibc: enable FENV support

[Waldemar Brodkorb]

Hi Thomas,
Thomas Petazzoni wrote,

> Hello,
> 
> On Sun, Aug 16, 2026 at 11:24:40AM +0200, Waldemar Brodkorb wrote:
> > Enable FENV support unconditionally when a hard-float toolchain is in use.
> > Useful for packages as quickjs and chawan.
> > Adds 24kb to the C library on aarch64.
> > 
> > Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
> 
> I am not 100% sure, but this seems to have broken the build of gcc
> 14.4.0 on x86 32-bit:
> 
>   https://autobuild.buildroot.net/?reason=host-gcc-final-14.4.0&libc=uclibc
> 
> Even though we've had gcc 14.4.0 for a while, this only started
> happening on August 16, first bad commit being 9ac19958, which is
> shortly after this fenv support in uClibc was enabled.
> 
> And the build failure clearly connects to fenv:
> 
> In file included from ../../../libquadmath/math/x2y2m1q.c:19:
> ../../../libquadmath/quadmath-imp.h:310:8: error: redefinition of 'struct rm_ctx'
>   310 | struct rm_ctx
>       |        ^~~~~~
> In file included from ../../../libquadmath/quadmath-imp.h:32:
> /home/autobuild/autobuild/instance-16/output-1/host/i686-buildroot-linux-uclibc/sysroot/usr/include/fenv.h:137:8: note: originally defined here
>   137 | struct rm_ctx
>       |        ^~~~~~
> 
> Could you have a look into this?

Yes, you are right. I always had libquadmath disabled in my
toolchains while testing. Fix sent to the BR mailinglist right now.

https://lists.buildroot.org/pipermail/buildroot/2026-August/807736.html

Thomas, are there any plans to update the Bootlin toolchains?

best regards
 Waldemar
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Re: [Buildroot] [PATCH] package/uclibc: enable FENV support

[Thomas Petazzoni via buildroot]

On Tue, Aug 18, 2026 at 08:21:05PM +0200, Waldemar Brodkorb wrote:
> Yes, you are right. I always had libquadmath disabled in my
> toolchains while testing. Fix sent to the BR mailinglist right now.
> 
> https://lists.buildroot.org/pipermail/buildroot/2026-August/807736.html

Thanks a lot!

> Thomas, are there any plans to update the Bootlin toolchains?

Yes, Romain Naour and I are working on it. This is why we've reported
several toolchain issues lately: because we've done a full build of
all toolchains, and discovered some issues.

Best regards,

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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