From: Peter Maydell <peter.maydell@linaro.org>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [PATCH 15/19] linux-user/arm: Replace ARM_FEATURE_VFP* tests for HWCAP
Date: Thu, 20 Feb 2020 17:32:33 +0000 [thread overview]
Message-ID: <CAFEAcA98CnJ8jhZ1AFWcmK+UE0RwZJHhwQtNnd4z5SG5QqEqjQ@mail.gmail.com> (raw)
In-Reply-To: <20200214181547.21408-16-richard.henderson@linaro.org>
On Fri, 14 Feb 2020 at 18:16, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Use isar feature tests instead of feature bit tests.
>
> Although none of QEMUs current cpus have VFPv3 without D32,
> replace the large comment explaining why with one line that
> sets ARM_HWCAP_ARM_VFPv3D16 under the correct conditions.
> Mirror the test sequence used in the linux kernel.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> linux-user/elfload.c | 24 +++++++++++++++---------
> 1 file changed, 15 insertions(+), 9 deletions(-)
>
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index f3080a1635..c52c814a2e 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -468,22 +468,28 @@ static uint32_t get_elf_hwcap(void)
>
> /* EDSP is in v5TE and above, but all our v5 CPUs are v5TE */
> GET_FEATURE(ARM_FEATURE_V5, ARM_HWCAP_ARM_EDSP);
> - GET_FEATURE(ARM_FEATURE_VFP, ARM_HWCAP_ARM_VFP);
> GET_FEATURE(ARM_FEATURE_IWMMXT, ARM_HWCAP_ARM_IWMMXT);
> GET_FEATURE(ARM_FEATURE_THUMB2EE, ARM_HWCAP_ARM_THUMBEE);
> GET_FEATURE(ARM_FEATURE_NEON, ARM_HWCAP_ARM_NEON);
> - GET_FEATURE(ARM_FEATURE_VFP3, ARM_HWCAP_ARM_VFPv3);
> GET_FEATURE(ARM_FEATURE_V6K, ARM_HWCAP_ARM_TLS);
> - GET_FEATURE(ARM_FEATURE_VFP4, ARM_HWCAP_ARM_VFPv4);
> + GET_FEATURE(ARM_FEATURE_LPAE, ARM_HWCAP_ARM_LPAE);
> +
> GET_FEATURE_ID(arm_div, ARM_HWCAP_ARM_IDIVA);
> GET_FEATURE_ID(thumb_div, ARM_HWCAP_ARM_IDIVT);
> - /* All QEMU's VFPv3 CPUs have 32 registers, see VFP_DREG in translate.c.
> - * Note that the ARM_HWCAP_ARM_VFPv3D16 bit is always the inverse of
> - * ARM_HWCAP_ARM_VFPD32 (and so always clear for QEMU); it is unrelated
> - * to our VFP_FP16 feature bit.
> + /*
> + * Note that none of QEMU's cpus have double precision without single
> + * precision support in VFP, so only test the single precision field.
> */
Why not actually mirror the kernel's test sequence, rather
than having a comment about how we deviate from it ?
> - GET_FEATURE(ARM_FEATURE_VFP3, ARM_HWCAP_ARM_VFPD32);
> - GET_FEATURE(ARM_FEATURE_LPAE, ARM_HWCAP_ARM_LPAE);
> + GET_FEATURE_ID(aa32_fpsp_v2, ARM_HWCAP_ARM_VFP);
> + if (cpu_isar_feature(aa32_fpsp_v3, cpu)) {
> + hwcaps |= ARM_HWCAP_ARM_VFPv3;
> + if (cpu_isar_feature(aa32_simd_r32, cpu)) {
> + hwcaps |= ARM_HWCAP_ARM_VFPD32;
> + } else {
> + hwcaps |= ARM_HWCAP_ARM_VFPv3D16;
> + }
> + }
> + GET_FEATURE_ID(aa32_simdfmac, ARM_HWCAP_ARM_VFPv4);
>
> return hwcaps;
> }
thanks
-- PMM
next prev parent reply other threads:[~2020-02-20 17:33 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 18:15 [PATCH 00/19] target/arm: vfp feature and decodetree cleanup Richard Henderson
2020-02-14 18:15 ` [PATCH 01/19] target/arm: Fix field extract from MVFR[0-2] Richard Henderson
2020-02-14 18:29 ` Philippe Mathieu-Daudé
2020-02-14 18:35 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 02/19] target/arm: Rename isar_feature_aa32_simd_r32 Richard Henderson
2020-02-14 18:50 ` Philippe Mathieu-Daudé
2020-02-21 15:58 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 03/19] target/arm: Use isar_feature_aa32_simd_r32 more places Richard Henderson
2020-02-21 16:02 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 04/19] target/arm: Set MVFR0.FPSP for ARMv5 cpus Richard Henderson
2020-02-21 16:02 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 05/19] target/arm: Add isar_feature_aa32_simd_r16 Richard Henderson
2020-02-21 16:01 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 06/19] target/arm: Rename isar_feature_aa32_fpdp_v2 Richard Henderson
2020-02-14 18:51 ` Philippe Mathieu-Daudé
2020-02-14 18:15 ` [PATCH 07/19] target/arm: Add isar_feature_aa32_{fpsp_v2, fpsp_v3, fpdp_v3} Richard Henderson
2020-02-21 16:03 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 08/19] target/arm: Perform fpdp_v2 check first Richard Henderson
2020-02-21 16:04 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 09/19] target/arm: Replace ARM_FEATURE_VFP3 checks with fp{sp, dp}_v3 Richard Henderson
2020-02-21 16:05 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 10/19] target/arm: Add missing checks for fpsp_v2 Richard Henderson
2020-02-21 16:05 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 11/19] target/arm: Replace ARM_FEATURE_VFP4 with isar_feature_aa32_simdfmac Richard Henderson
2020-02-20 16:37 ` Peter Maydell
2020-02-20 16:41 ` Peter Maydell
2020-02-20 17:55 ` Richard Henderson
2020-02-14 18:15 ` [PATCH 12/19] target/arm: Remove ARM_FEATURE_VFP check from disas_vfp_insn Richard Henderson
2020-02-20 17:19 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 13/19] target/arm: Move VLLDM and VLSTM to vfp.decode Richard Henderson
2020-02-20 17:02 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 14/19] target/arm: Move the vfp decodetree calls next to the base isa Richard Henderson
2020-02-20 17:16 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 15/19] linux-user/arm: Replace ARM_FEATURE_VFP* tests for HWCAP Richard Henderson
2020-02-20 17:32 ` Peter Maydell [this message]
2020-02-14 18:15 ` [PATCH 16/19] target/arm: Remove ARM_FEATURE_VFP* Richard Henderson
2020-02-20 17:33 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 17/19] target/arm: Add formats for some vfp 2 and 3-register insns Richard Henderson
2020-02-20 17:40 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 18/19] target/arm: Split VFM decode Richard Henderson
2020-02-20 17:45 ` Peter Maydell
2020-02-14 18:15 ` [PATCH 19/19] target/arm: Split VMINMAXNM decode Richard Henderson
2020-02-20 17:49 ` Peter Maydell
2020-02-14 20:11 ` [PATCH 00/19] target/arm: vfp feature and decodetree cleanup no-reply
2020-02-20 17:52 ` Peter Maydell
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