[llvmlinux] compile linux kernel for ARM with Clang-3.6

Charlebois, Mark mcharleb at quicinc.com
Thu Nov 13 22:51:41 UTC 2014

I'll try and have a look at the nexus 5 target over the weekend. I won't be able to work on it before then.


From: llvmlinux-bounces at lists.linuxfoundation.org <llvmlinux-bounces at lists.linuxfoundation.org> on behalf of Behan Webster <behanw at converseincode.com>
Sent: Thursday, November 13, 2014 2:48 PM
To: Davide Rombolà
Cc: llvm >> Compiling the Linux Kernel with Clang/LLVM
Subject: Re: [llvmlinux] compile linux kernel for ARM with Clang-3.6

The Nexus5 build is still a work in progress. Not yet working.

However, the error message you've posted makes it appear that the x86 version of the assembler is being called instead of the ARM one. No doubt since it is a 3.4 kernel it doesn't have all the appropriate patches in place since we spend a lot more time on the mainline patches.

Cross posting to the LLVMLinux list so that others who are interested might be able to help you.


On 11/13/14 10:13, Davide Rombolà wrote:

I'm on linux kernel 3.4 arch mach-msm (nexus 5), the error is:

/usr/bin/as: unrecognized option '-mfloat-abi=softfp' clang-3: error: assembler command failed with exit code 1

Il 13/nov/2014 18:43 "Behan Webster" <behanw at converseincode.com<mailto:behanw at converseincode.com>> ha scritto:
On 11/13/14 03:42, Davide Rombolà wrote:
i'm trying to compile linux kernel for arm with clang-3.5.
i followed this guide http://llvm.linuxfoundation.org/index.php/Main_Page and all went ok.
Depending on which kernel version you are building, you will need a clang newer than 3.5. Currently only the pre 3.6 clang will work.

On compilation clang gave me error on "-mfloat-abi=soft" flag.
I'd have to see the error. But remember that the kernel can't use floating point opcodes (with very few exceptions).

this flag only apper in "arch/arm/vfp/Makefile", i deleted it but clang still gave me the same error.

Could you suggest me a solution for this?

Thanks for your time,
Like I said, I'd need to see the error. I don't have enough info to be able to even guess.


Behan Webster
behanw at converseincode.com<mailto:behanw at converseincode.com>

Behan Webster
behanw at converseincode.com<mailto:behanw at converseincode.com>
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