From: Catalin Marinas <catalin.marinas@arm.com>
To: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH] arm64: Don't allow SVE to be used with BROKEN_GAS_INST
Date: Wed, 2 Mar 2022 13:58:13 +0000 [thread overview]
Message-ID: <Yh939U9dn7fvhKPz@arm.com> (raw)
In-Reply-To: <20220225184045.5502-1-broonie@kernel.org>
On Fri, Feb 25, 2022 at 06:40:45PM +0000, Mark Brown wrote:
> We support building the kernel with archaic versions of binutils which
> had some confusion regarding how instructions should be encoded for .inst
> which we work around with the __emit_inst() macro. Unfortunately we have
> not consistently used this macro, one of the places where it's missed being
> the macros that manually encode SVE instructions. This means that kernels
> built with such toolchains have never supported SVE correctly.
>
> Since these toolchains are very old (some idle research suggested 2015
> era) it seems more sensible to just refuse to build SVE support with them,
> in the unlikely event that someone has a need to use such a toolchain to
> build a kernel which will run on a system with SVE support they can always
> fix this properly but it seems more likely that we will deprecate support
> for these toolchains and remove __emit_inst() before that happens.
>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
> arch/arm64/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index f8e5f64fc40b..4312cc622277 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1899,6 +1899,7 @@ endmenu
> config ARM64_SVE
> bool "ARM Scalable Vector Extension support"
> default y
> + depends on !BROKEN_GAS_INST
It looks like it's not just SVE affected here. A grep for "\.inst\>"
shows a few places in the crypto code as well. How hard is it to use
__emit_inst() in these places?
--
Catalin
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-03-02 13:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-25 18:40 [PATCH] arm64: Don't allow SVE to be used with BROKEN_GAS_INST Mark Brown
2022-03-02 13:58 ` Catalin Marinas [this message]
2022-03-02 16:04 ` Mark Brown
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Yh939U9dn7fvhKPz@arm.com \
--to=catalin.marinas@arm.com \
--cc=broonie@kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.