From: "Cédric Le Goater" <clg@kaod.org>
To: qemu-arm@nongnu.org, qemu-devel@nongnu.org
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
"Richard Henderson" <richard.henderson@linaro.org>,
"Joel Stanley" <joel@jms.id.au>,
"Andrew Jeffery" <andrew@aj.id.au>,
"Cédric Le Goater" <clg@kaod.org>
Subject: [PATCH 1/2] target/arm: Disable VFPv4-D32 when NEON is not available
Date: Wed, 28 Sep 2022 18:47:18 +0200 [thread overview]
Message-ID: <20220928164719.655586-2-clg@kaod.org> (raw)
In-Reply-To: <20220928164719.655586-1-clg@kaod.org>
As the Cortex A7 MPCore Technical reference says :
"When FPU option is selected without NEON, the FPU is VFPv4-D16 and
uses 16 double-precision registers. When the FPU is implemented with
NEON, the FPU is VFPv4-D32 and uses 32 double-precision registers.
This register bank is shared with NEON."
Modify the mvfr0 register value of the cortex A7 to advertise only 16
registers when NEON is not available, and not 32 registers.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
target/arm/cpu.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 7ec3281da9aa..01dc74c32add 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1684,6 +1684,10 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
cpu->isar.id_isar6 = u;
if (!arm_feature(env, ARM_FEATURE_M)) {
+ u = cpu->isar.mvfr0;
+ u = FIELD_DP32(u, MVFR0, SIMDREG, 1); /* 16 registers */
+ cpu->isar.mvfr0 = u;
+
u = cpu->isar.mvfr1;
u = FIELD_DP32(u, MVFR1, SIMDLS, 0);
u = FIELD_DP32(u, MVFR1, SIMDINT, 0);
--
2.37.3
next prev parent reply other threads:[~2022-09-28 18:29 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-28 16:47 [PATCH 0/2] ast2600: Disable NEON and VFPv4-D32 Cédric Le Goater
2022-09-28 16:47 ` Cédric Le Goater [this message]
2022-09-28 17:21 ` [PATCH 1/2] target/arm: Disable VFPv4-D32 when NEON is not available Richard Henderson
2022-09-28 23:00 ` Joel Stanley
2022-09-29 7:20 ` Cédric Le Goater
2022-09-29 11:48 ` Peter Maydell
2022-09-29 11:44 ` Peter Maydell
2022-09-29 15:22 ` Richard Henderson
2022-09-29 15:29 ` Peter Maydell
2022-09-30 14:59 ` Cédric Le Goater
2022-09-30 15:10 ` Peter Maydell
2022-09-28 16:47 ` [PATCH 2/2] ast2600: Drop NEON from the CPU features Cédric Le Goater
2022-09-29 2:09 ` Joel Stanley
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