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Date: Tue, 14 Jun 2016 09:58:20 -0700
From: "Zhao, Weiming" <>
Subject: Re: build musl for armv7m

Thank you, Szabolcs.

It's GAS-only flag, clang's integrated-as doesn't support it. I can use 

It also expose other errors:

src/thread/arm/atomics.s:9: Error: cannot use register index with 
PC-relative addressing -- `ldr ip,[pc,ip]'

Clang's integrated-as accepts it but seems encoded incorrectly.

I can fix it.

On 6/14/2016 9:32 AM, Szabolcs Nagy wrote:
> * Zhao, Weiming <> [2016-06-14 09:12:17 -0700]:
>> I haven't did a full test as the functions I modified are not actually being
>> used.
>> It is a bare-metal environment, using clang to compile.
>> Main flags are -mcpu=cortex-m3 -Os -fdata-sections -ffunction-sections
>> -mno-unaligned-access
>> Could you please let me know the gas option?
> -mimplicit-it=always
>> Thanks,
>> Weiing
>> On 6/14/2016 6:00 AM, Rich Felker wrote:
>>> On Tue, Jun 14, 2016 at 01:49:40AM -0700, wrote:
>>>> Hi,
>>>> I'm building MUSL with -mcpu=cortex-m3. There are a few .s files
>>>> that cannot be assembled because: (1) use predicated instructions
>>>> without IT instr (2) use sp inside reg list in ldmia/stmia.
>>>> Please help to review the attached patch.
>>> Did you test anything? These patches do not result in working code;
>>> they just make it assemble without errors. There's already a gas
>>> option to automatically add IT instructions where needed for
>>> thumb-only targets, but that's not the only thing needed to support
>>> thumb-only/cortex-m. I'd be interested in knowing more about the setup
>>> you're trying to target. Is it Linux or bare-metal? If Linux, are you
>>> going to use the ARM/FDPIC toolchain & kernel mods? I'm about to leave
>>> at the moment but I'll follow up with a more detailed review of your
>>> patch later.
>>>> Also, is there any easy way of disabling string/arm/memcpy_le.S ?
>>>> For baremetal, unaligned access may be unavailable.
>>> That file does not perform any unaligned access. It should work on any
>>> EABI-supported version of the arm instruction set.
>>> Rich
>> -- 
>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

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