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Re: [Qemu-devel] [PATCH 1/2] Add dummy implementation of generic timer c
From: |
Andreas Färber |
Subject: |
Re: [Qemu-devel] [PATCH 1/2] Add dummy implementation of generic timer cp15 registers |
Date: |
Wed, 25 Jan 2012 15:01:27 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:9.0) Gecko/20111220 Thunderbird/9.0 |
Am 25.01.2012 14:32, schrieb Peter Maydell:
> Add a dummy implementation of the cp15 registers for the generic
> timer (found in the Cortex-A15), just sufficient for Linux to
> decide that it can't use it. This requires at least CNTP_CTL and
> CNTFRQ to be implemented as RAZ/WI; we RAZ/WI all of c14.
>
> Signed-off-by: Peter Maydell <address@hidden>
Reviewed-by: Andreas Färber <address@hidden>
Took me a bit to figure out RAZ/WI. ;)
Andreas
> ---
> target-arm/cpu.h | 1 +
> target-arm/helper.c | 12 ++++++++++--
> 2 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/target-arm/cpu.h b/target-arm/cpu.h
> index 42c53a7..7442c99 100644
> --- a/target-arm/cpu.h
> +++ b/target-arm/cpu.h
> @@ -382,6 +382,7 @@ enum arm_features {
> ARM_FEATURE_VAPA, /* cp15 VA to PA lookups */
> ARM_FEATURE_ARM_DIV, /* divide supported in ARM encoding */
> ARM_FEATURE_VFP4, /* VFPv4 (implies that NEON is v2) */
> + ARM_FEATURE_GENERIC_TIMER,
> };
>
> static inline int arm_feature(CPUARMState *env, int feature)
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index 22e40fc..5e7205a 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -1764,7 +1764,11 @@ void HELPER(set_cp15)(CPUState *env, uint32_t insn,
> uint32_t val)
> goto bad_reg;
> }
> break;
> - case 14: /* Reserved. */
> + case 14: /* Generic timer */
> + if (arm_feature(env, ARM_FEATURE_GENERIC_TIMER)) {
> + /* Dummy implementation: RAZ/WI for all */
> + break;
> + }
> goto bad_reg;
> case 15: /* Implementation specific. */
> if (arm_feature(env, ARM_FEATURE_XSCALE)) {
> @@ -2134,7 +2138,11 @@ uint32_t HELPER(get_cp15)(CPUState *env, uint32_t insn)
> default:
> goto bad_reg;
> }
> - case 14: /* Reserved. */
> + case 14: /* Generic timer */
> + if (arm_feature(env, ARM_FEATURE_GENERIC_TIMER)) {
> + /* Dummy implementation: RAZ/WI for all */
> + return 0;
> + }
> goto bad_reg;
> case 15: /* Implementation specific. */
> if (arm_feature(env, ARM_FEATURE_XSCALE)) {
--
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