From: Mark Brown <broonie@kernel.org>
To: Alan Hayward <Alan.Hayward@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>,
Will Deacon <will@kernel.org>,
Shuah Khan <skhan@linuxfoundation.org>,
Shuah Khan <shuah@kernel.org>,
Luis Machado <Luis.Machado@arm.com>,
Salil Akerkar <Salil.Akerkar@arm.com>,
Basant KumarDwivedi <Basant.KumarDwivedi@arm.com>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kselftest@vger.kernel.org"
<linux-kselftest@vger.kernel.org>, nd <nd@arm.com>
Subject: Re: [PATCH v1 12/38] arm64/sme: Provide ABI documentation for SME
Date: Fri, 8 Oct 2021 18:04:42 +0100 [thread overview]
Message-ID: <YWB6KmvHGfYBBoxK@sirena.org.uk> (raw)
In-Reply-To: <0749CCC0-CCEF-4869-9F55-FD9AC97CBA67@arm.com>
[-- Attachment #1: Type: text/plain, Size: 1486 bytes --]
On Fri, Oct 08, 2021 at 04:45:44PM +0000, Alan Hayward wrote:
> > On 8 Oct 2021, at 16:28, Mark Brown <broonie@kernel.org> wrote:
> > On Fri, Oct 08, 2021 at 02:11:46PM +0000, Alan Hayward wrote:
> >> Can NT_ARM_SSVE return a fpsimd?
> > It's documented that way for simplicity but in the current
> > implementation it won't ever actually do so in practice. The
> > only case where I could see that it might happen would be if we
> > change the syscalls to stay in streaming mode over syscall, in
> > that case we could do as we do for SVE and preserve FPSIMD
> > registers only. At present we drop out of streaming mode if we
> > get a syscall with it enabled so it's a non-issue, if people
> > agree that that's the right thing for the syscalls then we should
> > update the documentation to specify this since otherwise we'll
> > doubtless catch someone by surprise if we ever manage to start
> > doing it in the future.
> ….or it’ll end up executing some code that was written to cope with fpsimd, but has never been
> run. Might be worth making it explicit in the documentation.
I will if/when it gets fixed that way. Actually, while looking
at that code I was tempted to remove the support for returning
FPSIMD only registers via NT_ARM_SVE entirely and just always
convert to SVE format - I'm not sure what the use case was there?
It's not a pressing thing but it seemed like it was a bit of an
implementation detail that we were revealing.
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@kernel.org>
To: Alan Hayward <Alan.Hayward@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>,
Will Deacon <will@kernel.org>,
Shuah Khan <skhan@linuxfoundation.org>,
Shuah Khan <shuah@kernel.org>,
Luis Machado <Luis.Machado@arm.com>,
Salil Akerkar <Salil.Akerkar@arm.com>,
Basant KumarDwivedi <Basant.KumarDwivedi@arm.com>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kselftest@vger.kernel.org"
<linux-kselftest@vger.kernel.org>, nd <nd@arm.com>
Subject: Re: [PATCH v1 12/38] arm64/sme: Provide ABI documentation for SME
Date: Fri, 8 Oct 2021 18:04:42 +0100 [thread overview]
Message-ID: <YWB6KmvHGfYBBoxK@sirena.org.uk> (raw)
In-Reply-To: <0749CCC0-CCEF-4869-9F55-FD9AC97CBA67@arm.com>
[-- Attachment #1.1: Type: text/plain, Size: 1486 bytes --]
On Fri, Oct 08, 2021 at 04:45:44PM +0000, Alan Hayward wrote:
> > On 8 Oct 2021, at 16:28, Mark Brown <broonie@kernel.org> wrote:
> > On Fri, Oct 08, 2021 at 02:11:46PM +0000, Alan Hayward wrote:
> >> Can NT_ARM_SSVE return a fpsimd?
> > It's documented that way for simplicity but in the current
> > implementation it won't ever actually do so in practice. The
> > only case where I could see that it might happen would be if we
> > change the syscalls to stay in streaming mode over syscall, in
> > that case we could do as we do for SVE and preserve FPSIMD
> > registers only. At present we drop out of streaming mode if we
> > get a syscall with it enabled so it's a non-issue, if people
> > agree that that's the right thing for the syscalls then we should
> > update the documentation to specify this since otherwise we'll
> > doubtless catch someone by surprise if we ever manage to start
> > doing it in the future.
> ….or it’ll end up executing some code that was written to cope with fpsimd, but has never been
> run. Might be worth making it explicit in the documentation.
I will if/when it gets fixed that way. Actually, while looking
at that code I was tempted to remove the support for returning
FPSIMD only registers via NT_ARM_SVE entirely and just always
convert to SVE format - I'm not sure what the use case was there?
It's not a pressing thing but it seemed like it was a bit of an
implementation detail that we were revealing.
[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
[-- Attachment #2: Type: text/plain, Size: 176 bytes --]
_______________________________________________
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:[~2021-10-08 17:04 UTC|newest]
Thread overview: 143+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-30 18:11 [PATCH v1 00/38] arm64/sme: Initial support for the Scalable Matrix Extension Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 01/38] arm64/fp: Reindent fpsimd_save() Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-11 9:39 ` Jonathan Cameron
2021-10-11 9:39 ` Jonathan Cameron
2021-10-11 13:02 ` Mark Brown
2021-10-11 13:02 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 02/38] arm64/sve: Remove sve_load_from_fpsimd_state() Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 03/38] arm64/sve: Make access to FFR optional Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 04/38] arm64/sve: Rename find_supported_vector_length() Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 05/38] arm64/sve: Use accessor functions for vector lengths in thread_struct Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 06/38] arm64/sve: Put system wide vector length information into structs Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-01 3:13 ` kernel test robot
2021-10-01 3:13 ` kernel test robot
2021-10-01 3:13 ` kernel test robot
2021-09-30 18:11 ` [PATCH v1 07/38] arm64/sve: Explicitly load vector length when restoring SVE state Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 08/38] arm64/sve: Track vector lengths for tasks in an array Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-11 10:20 ` Jonathan Cameron
2021-10-11 10:20 ` Jonathan Cameron
2021-10-11 13:14 ` Mark Brown
2021-10-11 13:14 ` Mark Brown
2021-10-11 13:18 ` Jonathan Cameron
2021-10-11 13:18 ` Jonathan Cameron
2021-09-30 18:11 ` [PATCH v1 09/38] arm64/sve: Make sysctl interface for SVE reusable by SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 10/38] arm64/sve: Generalise vector length configuration prctl() for SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-11 10:27 ` Jonathan Cameron
2021-10-11 10:27 ` Jonathan Cameron
2021-10-11 13:18 ` Mark Brown
2021-10-11 13:18 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 11/38] selftests: arm64: Parameterise ptrace vector length information Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 12/38] arm64/sme: Provide ABI documentation for SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-08 14:11 ` Alan Hayward
2021-10-08 14:11 ` Alan Hayward
2021-10-08 15:28 ` Mark Brown
2021-10-08 15:28 ` Mark Brown
2021-10-08 16:45 ` Alan Hayward
2021-10-08 16:45 ` Alan Hayward
2021-10-08 17:04 ` Mark Brown [this message]
2021-10-08 17:04 ` Mark Brown
2021-10-11 11:15 ` Alan Hayward
2021-10-11 11:15 ` Alan Hayward
2021-10-11 11:48 ` Mark Brown
2021-10-11 11:48 ` Mark Brown
2021-10-11 11:05 ` Jonathan Cameron
2021-10-11 11:05 ` Jonathan Cameron
2021-10-11 13:20 ` Mark Brown
2021-10-11 13:20 ` Mark Brown
2021-10-11 13:17 ` Szabolcs Nagy
2021-10-11 13:17 ` Szabolcs Nagy
2021-10-11 13:23 ` Mark Brown
2021-10-11 13:23 ` Mark Brown
2021-10-11 14:19 ` Szabolcs Nagy
2021-10-11 14:19 ` Szabolcs Nagy
2021-10-11 20:10 ` Mark Brown
2021-10-11 20:10 ` Mark Brown
2021-10-12 8:23 ` Szabolcs Nagy
2021-10-12 8:23 ` Szabolcs Nagy
2021-10-13 18:37 ` Mark Brown
2021-10-13 18:37 ` Mark Brown
2021-10-14 9:57 ` Szabolcs Nagy
2021-10-14 9:57 ` Szabolcs Nagy
2021-09-30 18:11 ` [PATCH v1 13/38] arm64/sme: System register and exception syndrome definitions Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 14/38] arm64/sme: Define macros for manually encoding SME instructions Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 15/38] arm64/sme: Early CPU setup for SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 16/38] arm64/sme: Basic enumeration support Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 17/38] arm64/sme: Identify supported SME vector lengths at boot Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 18/38] arm64/sme: Implement sysctl to set the default vector length Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 19/38] arm64/sme: Implement vector length configuration prctl()s Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-01 5:20 ` kernel test robot
2021-10-01 5:20 ` kernel test robot
2021-10-01 5:20 ` kernel test robot
2021-10-01 12:40 ` Mark Brown
2021-10-01 12:40 ` Mark Brown
2021-10-01 12:40 ` Mark Brown
2021-10-08 1:32 ` [kbuild-all] " Chen, Rong A
2021-10-08 1:32 ` Chen, Rong A
2021-10-08 1:32 ` [kbuild-all] " Chen, Rong A
2021-10-01 16:38 ` kernel test robot
2021-10-01 16:38 ` kernel test robot
2021-10-01 16:38 ` kernel test robot
2021-09-30 18:11 ` [PATCH v1 20/38] arm64/sme: Implement support for TPIDR2 Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 21/38] arm64/sme: Implement SVCR context switching Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-11 12:15 ` Jonathan Cameron
2021-10-11 12:15 ` Jonathan Cameron
2021-09-30 18:11 ` [PATCH v1 22/38] arm64/sme: Implement streaming SVE " Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 23/38] arm64/sme: Implement ZA " Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-11 12:27 ` Jonathan Cameron
2021-10-11 12:27 ` Jonathan Cameron
2021-09-30 18:11 ` [PATCH v1 24/38] arm64/sme: Implement traps and syscall handling for SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-10-11 12:37 ` Jonathan Cameron
2021-10-11 12:37 ` Jonathan Cameron
2021-09-30 18:11 ` [PATCH v1 25/38] arm64/sme: Implement streaming SVE signal handling Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 26/38] arm64/sme: Implement ZA " Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 27/38] arm64/sme: Implement ptrace support for streaming mode SVE registers Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 28/38] arm64/sme: Add ptrace support for ZA Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 29/38] arm64/sme: Disable streaming mode and ZA when flushing CPU state Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 30/38] arm64/sme: Save and restore streaming mode over EFI runtime calls Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 31/38] arm64/sme: Provide Kconfig for SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 32/38] kselftest/arm64: Add tests for TPIDR2 Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 33/38] kselftest/arm64: Extend vector configuration API tests to cover SME Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 34/38] kselftest/arm64: sme: Provide streaming mode SVE stress test Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 35/38] kselftest/arm64: Add stress test for SME ZA context switching Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 36/38] kselftest/arm64: signal: Add SME signal handling tests Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 37/38] selftests: arm64: Add streaming SVE to SVE ptrace tests Mark Brown
2021-09-30 18:11 ` Mark Brown
2021-09-30 18:11 ` [PATCH v1 38/38] selftests: arm64: Add coverage for the ZA ptrace interface Mark Brown
2021-09-30 18:11 ` 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=YWB6KmvHGfYBBoxK@sirena.org.uk \
--to=broonie@kernel.org \
--cc=Alan.Hayward@arm.com \
--cc=Basant.KumarDwivedi@arm.com \
--cc=Catalin.Marinas@arm.com \
--cc=Luis.Machado@arm.com \
--cc=Salil.Akerkar@arm.com \
--cc=Szabolcs.Nagy@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=nd@arm.com \
--cc=shuah@kernel.org \
--cc=skhan@linuxfoundation.org \
--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.