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Date: Sun, 25 Oct 2009 13:23:44 +0100
Message-ID: <761ea48b0910250523t513f6c54t6bade67aef71cd0a@mail.gmail.com>
Subject: Re: [Qemu-devel] [PATCH v2 03/10] target-arm: allow modifying vfp
	fpexc en bit only
From: Laurent Desnogues <laurent.desnogues@gmail.com>
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To: juha.riihimaki@nokia.com
Cc: qemu-devel@nongnu.org

On Sat, Oct 24, 2009 at 1:19 PM,  <juha.riihimaki@nokia.com> wrote:
> From: Juha Riihim=E4ki <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 Riihim=E4ki <juha.riihimaki@nokia.com>
> ---
> =A0target-arm/translate.c | =A0 =A03 +++
> =A01 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, DisasCont=
ext *s, uint32_t insn)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 case ARM_VFP_FPEXC:
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (IS_USER(s))
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 return 1;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0/* TODO: VFP sub=
architecture support.
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 * For now, keep=
 the EN bit only */
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0tcg_gen_andi_i32=
(tmp, tmp, 1 << 30);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 store_cpu_field(t=
mp, vfp.xregs[rn]);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 gen_lookup_tb(s);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 break;
> --
> 1.6.5
>
>
>
>