Thread (13 messages) flat view 13 messages, 4 authors, 2019-08-07

Re: [PATCH] arm64: Disable big endian builds with clang

From: Nick Desaulniers <ndesaulniers@google.com>
Date: 2019-08-06 23:47:50

On Tue, Aug 6, 2019 at 2:25 PM Nick Desaulniers [off-list ref] wrote:
On Tue, Aug 6, 2019 at 11:39 AM Mark Brown [off-list ref] wrote:
quoted
Current boot tests with clang built big endian kernels in KernelCI are
showing problems with the kernel being unable to interpret big endian
userspace. This is a bug and should be fixed but for now let's prevent
these kernels being built, we may end up needing to add a version
dependency on the compiler anyway.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://github.com/ClangBuiltLinux/linux/issues/628
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
+Huck
Huck notes that the device eventually boots in qemu, it just takes on
the order of 165 seconds to boot.  What's the timeout on KernelCI?

I think if we can determine why we see:
[  144.626755] request_module: kmod_concurrent_max (0) close to 0
(max_modprobes: 50), for module binfmt-4c46, throttling...
[  149.752826] request_module: modprobe binfmt-4c46 cannot be
processed, kmod busy with 50 threads for more than 5 seconds now

a lot, then we don't actually need to disable this outright when
building w/ Clang?
quoted
---

The clang people (CCed) are aware and looking into this.

 arch/arm64/Kconfig | 1 +
 1 file changed, 1 insertion(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 990fdcbf05c7..1c32d9889e0f 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -813,6 +813,7 @@ config ARM64_PA_BITS

 config CPU_BIG_ENDIAN
        bool "Build big-endian kernel"
+       depends on !CC_IS_CLANG
        help
          Say Y if you plan on running a kernel in big-endian mode.
-- 
Thanks,
~Nick Desaulniers

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