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Re: ARM inline assembly usage in Linux kernel
- From: Renato Golin <renato dot golin at linaro dot org>
- To: ramrad01 at arm dot com
- Cc: Andrew Pinski <pinskia at gmail dot com>, Saleem Abdulrasool <compnerd at compnerd dot org>, GCC Mailing List <gcc at gcc dot gnu dot org>, Richard Sandiford <rsandifo at linux dot vnet dot ibm dot com>
- Date: Thu, 20 Feb 2014 13:17:02 +0000
- Subject: Re: ARM inline assembly usage in Linux kernel
- Authentication-results: sourceware.org; auth=none
- References: <20140219025428 dot GA5417 at lithium dot compnerd dot org> <CA+=Sn1kr+Vjf8bRRvg7nTzdPw3YCgHPYff4vFBEyN3jJFcZRQw at mail dot gmail dot com> <87sirfjovh dot fsf at sandifor-thinkpad dot stglab dot manchester dot uk dot ibm dot com> <CAMSE1kc3e=o1PxZj06ZUmxT+qbYrTz6oqELgDOGW8roOvWEZMQ at mail dot gmail dot com> <CA+=Sn1=hk63Fna77h1aWypaZt=p+u-4XzuO303=aWOZri=5Tsw at mail dot gmail dot com> <CAMSE1kcN9m_Wp-cCA_UfPJBeSkJwkHPqVv0CjjKCa4hwuF_GTQ at mail dot gmail dot com> <CAJA7tRZUFqP2CWj-nocqNvpyOnU6uJFAvqPXd2HCZnY=Le_7EA at mail dot gmail dot com>
On 20 February 2014 12:59, Ramana Radhakrishnan
<ramana.gcc@googlemail.com> wrote:
> It's not really because GAS supports it, but there exists a large body
> of code out there which uses inline assembler with pre-UAL syntax. I'm
> not sure people will appreciate a blanket break in one version of the
> toolchain and especially when people could quite easily mix and match
> between compiler versions and binutils versions.
Hi Ramana,
I agree, I didn't mean it was GAS' fault.
> Before anything else the compiler needs to be fixed and there are some
> corner cases to deal with build attributes especially for Thumb1 in
> the assembler before we can starting thinking about deprecating
> pre-UAL syntax.
Absolutely. But there needs to be an interest in the GNU community to
drive these changes forward. In LLVM we're very much pro-UAL and it
took us quite a lot of convincing to support pre-UAL syntax in the
*parser only*, but we'll never generate it ourselves. Everything we
generate is (or should be) UAL.
> It may be of
> interest for 4.9 + 1 = (4.10 /5.0) in GCC and the next binutils
> revision.
If people are really interested, I can start the ball rolling in the
binutils list.
> Adding the warning by default to GAS is just part of the solution.
It'll only be the second step, yes, with the first one being to fix
the remaining ugly bugs. There will be many more...
cheers,
--renato