From: Peter Maydell <peter.maydell@linaro.org>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: qemu-arm <qemu-arm@nongnu.org>, QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [PATCH v2 0/3] target/arm: Add sve-default-vector-length cpu property
Date: Mon, 26 Jul 2021 13:42:45 +0100 [thread overview]
Message-ID: <CAFEAcA_AKpibWQuX4gapGD+u=KCL9-er-ejPGS_cVyNbsuLJJQ@mail.gmail.com> (raw)
In-Reply-To: <20210723203344.968563-1-richard.henderson@linaro.org>
On Fri, 23 Jul 2021 at 21:34, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> This is intended to resolve #482.
>
> Changes for v2:
> * Split out length bounding fix to new patch.
> * Use byte units for sve-default-vector-length.
> * Support undocumented -1 "maximum".
> * Add documentation.
I'm going to apply this to target-arm.next with the following
docs tweak squashed into patch 3:
diff --git a/docs/system/arm/cpu-features.rst b/docs/system/arm/cpu-features.rst
index 4ff36cc83f0..7b97df442aa 100644
--- a/docs/system/arm/cpu-features.rst
+++ b/docs/system/arm/cpu-features.rst
@@ -379,11 +379,14 @@ example's (1), (4), and (6) exhibit recommended
uses of the properties.
SVE User-mode Default Vector Length Property
--------------------------------------------
-For qemu-aarch64, the cpu property `sve-default-vector-length=N` is
+For qemu-aarch64, the cpu property ``sve-default-vector-length=N`` is
defined to mirror the Linux kernel parameter file
-`/proc/sys/abi/sve_default_vector_length`. The default length, `N`,
-is in units of bytes and must be between 16 and 8192.
+``/proc/sys/abi/sve_default_vector_length``. The default length, ``N``,
+is in units of bytes and must be between 16 and 8192.
If not specified, the default vector length is 64.
If the default length is larger than the maximum vector length enabled
-with `sve<N>` properties, the actual vector length will be reduced.
+with ``sve<N>`` properties, the actual vector length will be reduced.
+
+If this property is set to ``-1`` then the default vector length
+is set to the maximum possible length.
thanks
-- PMM
next prev parent reply other threads:[~2021-07-26 12:44 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-23 20:33 [PATCH v2 0/3] target/arm: Add sve-default-vector-length cpu property Richard Henderson
2021-07-23 20:33 ` [PATCH v2 1/3] target/arm: Correctly bound length in sve_zcr_get_valid_len Richard Henderson
2021-07-26 10:57 ` Peter Maydell
2021-07-23 20:33 ` [PATCH v2 2/3] target/arm: Export aarch64_sve_zcr_get_valid_len Richard Henderson
2021-07-26 10:57 ` Peter Maydell
2021-07-23 20:33 ` [PATCH v2 3/3] target/arm: Add sve-default-vector-length cpu property Richard Henderson
2021-07-26 11:07 ` Peter Maydell
2021-07-26 14:59 ` Andrew Jones
2021-07-26 18:33 ` Richard Henderson
2021-07-26 18:40 ` Andrew Jones
2021-07-26 19:31 ` Peter Maydell
2021-07-26 12:42 ` Peter Maydell [this message]
2021-07-26 15:00 ` [PATCH v2 0/3] " Andrew Jones
2021-07-26 15:41 ` Peter Maydell
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