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Re: [PATCH v2 05/17] target/arm: Improve ID_AA64PFR0 FP/SIMD validation
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From: |
Peter Maydell |
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Subject: |
Re: [PATCH v2 05/17] target/arm: Improve ID_AA64PFR0 FP/SIMD validation |
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Date: |
Tue, 25 Feb 2020 15:58:28 +0000 |
On Tue, 25 Feb 2020 at 15:55, Richard Henderson
<address@hidden> wrote:
>
> On 2/25/20 5:24 AM, Peter Maydell wrote:
> > This check is supposed to be "did the user accidentally specify
> > some incompatible settings on their '-cpu,+this,-that' option?".
> > By making it check the actual ID register values, you're turning
> > it into also a check on "does the implementation specify sane
> > ID register values", which (a) is useful for TCG but ought to
> > be an assert and (b) we shouldn't be checking for KVM in case
> > the h/w is giving us dubious ID values.
>
> Hmm. Because kvm64 unconditionally set VFP and NEON, you're right. It was
> only kvm32 that was examining id registers.
>
> The only consequence of kvm giving us dubious id values that I can see is if
> ADVSIMD is on, but FP is off, we won't migrate the register set.
>
> Do you want me to add a tcg_enabled check, or shall we just drop the patch?
> The existing test is good enough for just checking the command-line.
If it isn't a requirement for the rest of the series, let's just
drop the patch.
thanks
-- PMM
- [PATCH v2 00/17] target/arm: vfp feature and decodetree cleanup, Richard Henderson, 2020/02/24
- [PATCH v2 02/17] target/arm: Rename isar_feature_aa32_fpdp_v2, Richard Henderson, 2020/02/24
- [PATCH v2 03/17] target/arm: Add isar_feature_aa32_{fpsp_v2, fpsp_v3, fpdp_v3}, Richard Henderson, 2020/02/24
- [PATCH v2 01/17] target/arm: Add isar_feature_aa32_vfp_simd, Richard Henderson, 2020/02/24
- [PATCH v2 05/17] target/arm: Improve ID_AA64PFR0 FP/SIMD validation, Richard Henderson, 2020/02/24
[PATCH v2 04/17] target/arm: Add isar_feature_aa64_fp_simd, isar_feature_aa32_vfp, Richard Henderson, 2020/02/24
[PATCH v2 07/17] target/arm: Replace ARM_FEATURE_VFP3 checks with fp{sp, dp}_v3, Richard Henderson, 2020/02/24
[PATCH v2 06/17] target/arm: Perform fpdp_v2 check first, Richard Henderson, 2020/02/24
[PATCH v2 08/17] target/arm: Add missing checks for fpsp_v2, Richard Henderson, 2020/02/24
[PATCH v2 09/17] target/arm: Replace ARM_FEATURE_VFP4 with isar_feature_aa32_simdfmac, Richard Henderson, 2020/02/24
[PATCH v2 10/17] target/arm: Remove ARM_FEATURE_VFP check from disas_vfp_insn, Richard Henderson, 2020/02/24
[PATCH v2 11/17] target/arm: Move VLLDM and VLSTM to vfp.decode, Richard Henderson, 2020/02/24