Re: [Qemu-devel] [PATCH v2 03/10] target-arm: allow modifying vfp fpexc en bit only

[Laurent Desnogues <laurent.desnogues@gmail.com>]

On Sat, Oct 24, 2009 at 1:19 PM,  <juha.riihimaki@nokia.com> wrote:
> From: Juha Riihimäki <juha.riihimaki@nokia.com>
>
> All other bits except for the EN in the VFP FPEXC register are defined
> as subarchitecture specific and real functionality for any of the
> other bits has not been implemented in QEMU. However, current code
> allows modifying all bits in the VFP FPEXC register leading to
> problems when guest code is writing 1's to the subarchitecture
> specific bits and checking whether the bits stay up to verify the
> existence of functionality which in fact does not exist in QEMU.

Shouldn't writes to FPEXC from gdb be protected in the same
way?  Except for that I agree with your patch.


Laurent

> Signed-off-by: Juha Riihimäki <juha.riihimaki@nokia.com>
> ---
>  target-arm/translate.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/target-arm/translate.c b/target-arm/translate.c
> index 09c996d..8cb1c0f 100644
> --- a/target-arm/translate.c
> +++ b/target-arm/translate.c
> @@ -2788,6 +2788,9 @@ static int disas_vfp_insn(CPUState * env, DisasContext *s, uint32_t insn)
>                         case ARM_VFP_FPEXC:
>                             if (IS_USER(s))
>                                 return 1;
> +                            /* TODO: VFP subarchitecture support.
> +                             * For now, keep the EN bit only */
> +                            tcg_gen_andi_i32(tmp, tmp, 1 << 30);
>                             store_cpu_field(tmp, vfp.xregs[rn]);
>                             gen_lookup_tb(s);
>                             break;
> --
> 1.6.5
>
>
>
>