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[PATCH v1 17/28] target/arm: default SVE length to 64 bytes for linux-us
From: |
Alex Bennée |
Subject: |
[PATCH v1 17/28] target/arm: default SVE length to 64 bytes for linux-user |
Date: |
Mon, 16 Mar 2020 17:21:44 +0000 |
The Linux kernel chooses the default of 64 bytes for SVE registers on
the basis that it is the largest size on known hardware that won't
grow the signal frame. We still honour the sve-max-vq property and
userspace can expand the number of lanes by calling PR_SVE_SET_VL.
This should not make any difference to SVE enabled software as the SVE
is of course vector length agnostic.
Signed-off-by: Alex Bennée <address@hidden>
Reviewed-by: Richard Henderson <address@hidden>
---
v2
- tweak zcr_el[1] instead
v7
- better form
---
target/arm/cpu.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 3623ecefbd9..0909ce86a12 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -195,9 +195,10 @@ static void arm_cpu_reset(CPUState *s)
env->cp15.cpacr_el1 = deposit64(env->cp15.cpacr_el1, 20, 2, 3);
/* and to the SVE instructions */
env->cp15.cpacr_el1 = deposit64(env->cp15.cpacr_el1, 16, 2, 3);
- /* with maximum vector length */
- env->vfp.zcr_el[1] = cpu_isar_feature(aa64_sve, cpu) ?
- cpu->sve_max_vq - 1 : 0;
+ /* with reasonable vector length */
+ if (cpu_isar_feature(aa64_sve, cpu)) {
+ env->vfp.zcr_el[1] = MIN(cpu->sve_max_vq - 1, 3);
+ }
/*
* Enable TBI0 and TBI1. While the real kernel only enables TBI0,
* turning on both here will produce smaller code and otherwise
--
2.20.1
- Re: [PATCH v1 13/28] target/i386: use gdb_get_reg helpers, (continued)
- [PATCH v1 15/28] target/arm: prepare for multiple dynamic XMLs, Alex Bennée, 2020/03/16
- [PATCH v1 28/28] gdbstub: Fix single-step issue by confirming 'vContSupported+' feature to gdb, Alex Bennée, 2020/03/16
- [PATCH v1 14/28] gdbstub: extend GByteArray to read register helpers, Alex Bennée, 2020/03/16
- [PATCH v1 24/28] tests/tcg/aarch64: add SVE iotcl test, Alex Bennée, 2020/03/16
- Re: [PATCH v1 24/28] tests/tcg/aarch64: add SVE iotcl test, Aleksandar Markovic, 2020/03/17
[PATCH v1 17/28] target/arm: default SVE length to 64 bytes for linux-user,
Alex Bennée <=
[PATCH v1 22/28] tests/guest-debug: add a simple test runner, Alex Bennée, 2020/03/16
[PATCH v1 18/28] target/arm: generate xml description of our SVE registers, Alex Bennée, 2020/03/16
[PATCH v1 21/28] configure: allow user to specify what gdb to use, Alex Bennée, 2020/03/16
[PATCH v1 20/28] tests/tcg/aarch64: userspace system register test, Alex Bennée, 2020/03/16