[Buildroot] [PATCH] package/glibc: only supports ARC little-endian since glibc 2.41

[Buildroot] [PATCH] package/glibc: only supports ARC little-endian since glibc 2.41

[Thomas Petazzoni via buildroot]

Since upstream commit
https://sourceware.org/git/?p=glibc.git;a=commit;h=4ff55d08df0e6f11cbd217f4dca4532bd7d9330d,
glibc no longer supports ARC big-endian, and the configure step fails
with:

checking for egrep -e... (cached) /bin/grep -E
checking for big endian... yes
configure: error: big-endian not supported
make: *** [package/pkg-generic.mk:263: /home/buildroot/instance-0/output-1/build/glibc-2.41-70-g1502c248d58cb99a203731707987a4342926e830/.stamp_configured] Error 1

This commit was first merged in glibc 2.41, so this issue is
applicable to both master (glibc 2.42) and 2025.02.x (glibc 2.41).

Fixes:

  https://autobuild.buildroot.net/results/87e4b84f3aee64d041c3b845cb003e6b90649ffb/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
---
 package/glibc/Config.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/package/glibc/Config.in b/package/glibc/Config.in
index 9a4fe6f3db..b066616a01 100644
--- a/package/glibc/Config.in
+++ b/package/glibc/Config.in
@@ -21,7 +21,7 @@ config BR2_PACKAGE_GLIBC_ARCH_SUPPORTS
 	default y if BR2_sparc64
 	default y if BR2_x86_64
 	default y if BR2_microblaze
-	default y if BR2_arc && BR2_ARC_ATOMIC_EXT && !BR2_arc750d && !BR2_arc770d
+	default y if BR2_arcle && BR2_ARC_ATOMIC_EXT && !BR2_arc750d && !BR2_arc770d
 	depends on !BR2_POWERPC_CPU_HAS_SPE
 	# glibc needs atomic instructions, and does not support
 	# single-precision floating point ABIs (ilp32f and lp64f)
-- 
2.51.1

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Re: [Buildroot] [PATCH] package/glibc: only supports ARC little-endian since glibc 2.41

[Peter Korsgaard]

>>>>> "Thomas" == Thomas Petazzoni via buildroot <buildroot@buildroot.org> writes:

 > Since upstream commit
 > https://sourceware.org/git/?p=glibc.git;a=commit;h=4ff55d08df0e6f11cbd217f4dca4532bd7d9330d,
 > glibc no longer supports ARC big-endian, and the configure step fails
 > with:

 > checking for egrep -e... (cached) /bin/grep -E
 > checking for big endian... yes
 > configure: error: big-endian not supported
 > make: *** [package/pkg-generic.mk:263: /home/buildroot/instance-0/output-1/build/glibc-2.41-70-g1502c248d58cb99a203731707987a4342926e830/.stamp_configured] Error 1

 > This commit was first merged in glibc 2.41, so this issue is
 > applicable to both master (glibc 2.42) and 2025.02.x (glibc 2.41).

 > Fixes:

 >   https://autobuild.buildroot.net/results/87e4b84f3aee64d041c3b845cb003e6b90649ffb/

 > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

Committed, thanks.

Does this mean we should completely drop support for big engian ARC?

-- 
Bye, Peter Korsgaard
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Re: [Buildroot] [PATCH] package/glibc: only supports ARC little-endian since glibc 2.41

[Thomas Petazzoni via buildroot]

Hello,

+Synopsys/ARC people in Cc.

On Sat, 06 Dec 2025 07:36:52 +0100
Peter Korsgaard <peter@korsgaard.com> wrote:

> Does this mean we should completely drop support for big engian ARC?

config BR2_PACKAGE_UCLIBC_ARCH_SUPPORTS
        bool
        default y if BR2_aarch64
        default y if BR2_aarch64_be
        default y if BR2_arcle
        default y if BR2_arceb

so I'd say no we don't need to drop support for big endian ARC as
uClibc still supports it.

However, I must say we have quite a few ARC-specific issues, which I
have reported a while ago to the Synopsys people, and there's no longer
any Synopsys participation to Buildroot. So I'm thinking we should
probably take this as a "Synopsys no longer cares" and therefore we
should drop support for ARC.

Let's see if they react to this e-mail. If they don't, it will be a
clear signal that they don't care anymore, and we should drop ARC.

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/glibc: only supports ARC little-endian since glibc 2.41

[Alexey Brodkin via buildroot]

Hi Thomas, Peter, all,

Synopsys ARC person here ;)

> > Does this mean we should completely drop support for big engian ARC?
> 
> config BR2_PACKAGE_UCLIBC_ARCH_SUPPORTS
>         bool
>         default y if BR2_aarch64
>         default y if BR2_aarch64_be
>         default y if BR2_arcle
>         default y if BR2_arceb
> 
> so I'd say no we don't need to drop support for big endian ARC as
> uClibc still supports it.

I think indeed, we may remove all the big-endian support for ARC.
Reasons are since introduction of ARC HS4x processors we no longer support
big-endian in any new processor IP, and even for older IP which used to
support big-endian it was rarely used... so basically there's no good justification
to spend any cycles on big-endian support looking forward in this project.
I.e. BE support in uClibc could also be removed if it makes any difference.
 
> However, I must say we have quite a few ARC-specific issues, which I
> have reported a while ago to the Synopsys people, and there's no longer
> any Synopsys participation to Buildroot. So I'm thinking we should
> probably take this as a "Synopsys no longer cares" and therefore we
> should drop support for ARC.

> Let's see if they react to this e-mail. If they don't, it will be a
> clear signal that they don't care anymore, and we should drop ARC.

Well, I must confess that indeed quite some activities (including Buildroot
support for ARC) were deprioritized some time ago due to resource
reallocation to other areas which were not that polished as our open-source
components. But even though I don't think that situation will change in
comings weeks, support of ARC HS (both v2 & v3, AKA HS3x, 4x, 5x and 6x)
in Buildroot and other open source projects is very important for us as one
of the key enablers for ARC Processor IP, thus by all means I'd like to see
corresponding support in.

Also, I have some ideas on how to apply some more love to ARC support
in Buildroot - let me explore that possibility as we do want to keep
at least existing ARC support in Buildroot and other open-source projects.

And thank you for all the work and care!

Regards,
Alexey
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Re: [Buildroot] [PATCH] package/glibc: only supports ARC little-endian since glibc 2.41

[Arnout Vandecappelle via buildroot]

In reply of:
> Since upstream commit
> https://sourceware.org/git/?p=glibc.git;a=commit;h=4ff55d08df0e6f11cbd217f4dca4532bd7d9330d,
> glibc no longer supports ARC big-endian, and the configure step fails
> with:
> 
> checking for egrep -e... (cached) /bin/grep -E
> checking for big endian... yes
> configure: error: big-endian not supported
> make: *** [package/pkg-generic.mk:263: /home/buildroot/instance-0/output-1/build/glibc-2.41-70-g1502c248d58cb99a203731707987a4342926e830/.stamp_configured] Error 1
> 
> This commit was first merged in glibc 2.41, so this issue is
> applicable to both master (glibc 2.42) and 2025.02.x (glibc 2.41).
> 
> Fixes:
> 
>   https://autobuild.buildroot.net/results/87e4b84f3aee64d041c3b845cb003e6b90649ffb/
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

Applied to 2025.02.x and 2025.08.x. Thanks

> ---
>  package/glibc/Config.in | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/package/glibc/Config.in b/package/glibc/Config.in
> index 9a4fe6f3db..b066616a01 100644
> --- a/package/glibc/Config.in
> +++ b/package/glibc/Config.in
> @@ -21,7 +21,7 @@ config BR2_PACKAGE_GLIBC_ARCH_SUPPORTS
>  	default y if BR2_sparc64
>  	default y if BR2_x86_64
>  	default y if BR2_microblaze
> -	default y if BR2_arc && BR2_ARC_ATOMIC_EXT && !BR2_arc750d && !BR2_arc770d
> +	default y if BR2_arcle && BR2_ARC_ATOMIC_EXT && !BR2_arc750d && !BR2_arc770d
>  	depends on !BR2_POWERPC_CPU_HAS_SPE
>  	# glibc needs atomic instructions, and does not support
>  	# single-precision floating point ABIs (ilp32f and lp64f)
> -- 
> 2.51.1
> 
> _______________________________________________
> buildroot mailing list
> buildroot@buildroot.org
> https://lists.buildroot.org/mailman/listinfo/buildroot
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Re: [Buildroot] [PATCH] package/glibc: only supports ARC little-endian since glibc 2.41

[Thomas Petazzoni via buildroot]

Hello Alexey,

On Tue, 9 Dec 2025 14:06:16 +0000
Alexey Brodkin <Alexey.Brodkin@synopsys.com> wrote:

> Synopsys ARC person here ;)

Good, thanks for your feedback!

> I think indeed, we may remove all the big-endian support for ARC.
> Reasons are since introduction of ARC HS4x processors we no longer support
> big-endian in any new processor IP, and even for older IP which used to
> support big-endian it was rarely used... so basically there's no good justification
> to spend any cycles on big-endian support looking forward in this project.
> I.e. BE support in uClibc could also be removed if it makes any difference.

Based on your feedback, I've sent a patch to completely drop support
for ARCeb:

  https://lore.kernel.org/buildroot/20251211161615.503688-1-thomas.petazzoni@bootlin.com/

> Well, I must confess that indeed quite some activities (including Buildroot
> support for ARC) were deprioritized some time ago due to resource
> reallocation to other areas which were not that polished as our open-source
> components. But even though I don't think that situation will change in
> comings weeks, support of ARC HS (both v2 & v3, AKA HS3x, 4x, 5x and 6x)
> in Buildroot and other open source projects is very important for us as one
> of the key enablers for ARC Processor IP, thus by all means I'd like to see
> corresponding support in.
> 
> Also, I have some ideas on how to apply some more love to ARC support
> in Buildroot - let me explore that possibility as we do want to keep
> at least existing ARC support in Buildroot and other open-source projects.

Thanks for your feedback. However, we can't support ARC in Buildroot if
there's not some minimal involvement from Synopsys to fix the
architecture-specific issues.

On August 21, 2024, I sent to you and Yuriy Kolerov an e-mail about ARC
toolchain issues.

On December 1, 2024, I sent another e-mail about ARC toolchain issues.

On December 27, 2024, I pinged again about this issue, and adding some
more.

On August 29, 2025, I reported again some other issue with ARC
toolchains.

This last problem still exists:

  https://autobuild.buildroot.net/results/be8/be8a35c9b07116f7de611c4b5ab821d500a2b12d/build-end.log
  https://autobuild.buildroot.net/results/b76/b768be74b5a5bce84b0172091f3f8720279f1028/build-end.log

The ARC-specific binutils version fails to build under some conditions:

  https://autobuild.buildroot.net/results/827/827708f47176368aac6439692c6e43ff6f2a0487/build-end.log

I understand that you may not be able to go through all build issues
affecting ARC, because many of them are not ARC-specific. Precisely
because I understand that, I have pointed out to you the specific build
issues that are ARC-specific, hoping that someone from Synopsys would
have a look.

So if by all means you would like to see the ARC support stay in
Buildroot, then Synopsys needs to dedicate a little bit of engineering
time to resolving the ARC-specific build issues. Do you think this
would be possible?

Thanks a lot for your support!

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