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Re: [Qemu-devel] [PATCH] arm-linux-user: fix elfload.c's AT_HWCAP reflec
From: |
Andreas Färber |
Subject: |
Re: [Qemu-devel] [PATCH] arm-linux-user: fix elfload.c's AT_HWCAP reflected cpu features. |
Date: |
Wed, 09 Nov 2011 14:34:41 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20110929 Thunderbird/7.0.1 |
Am 09.11.2011 14:04, schrieb Benoît Canet:
> The cpu capabilities passed by the elf loader in AT_HWCAP where
> a constant.
> Make AT_HWCAP reflect the emulated cpu features in order to give
> correct clues to eglibc.
>
> Fix : [Bug 887516] [NEW] VFP support reported for the PXA270
>
> Signed-off-by: Benoit Canet <address@hidden>
> ---
> linux-user/elfload.c | 31 +++++++++++++++++++++++++++----
> 1 files changed, 27 insertions(+), 4 deletions(-)
>
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index a413976..5d81ec1 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -375,10 +375,33 @@ bool guest_validate_base(unsigned long guest_base)
> return 1; /* All good */
> }
>
> -#define ELF_HWCAP (ARM_HWCAP_ARM_SWP | ARM_HWCAP_ARM_HALF \
> - | ARM_HWCAP_ARM_THUMB | ARM_HWCAP_ARM_FAST_MULT \
> - | ARM_HWCAP_ARM_FPA | ARM_HWCAP_ARM_VFP \
> - | ARM_HWCAP_ARM_NEON | ARM_HWCAP_ARM_VFPv3 )
> +
> +#define ELF_HWCAP get_elf_hwcap()
I assume ELF_HWCAP is being used in architecture-independent code? Or
would it be feasible to replace all occurrences with the function call?
> +
> +static uint32_t get_elf_hwcap(void)
> +{
> + CPUState *e = thread_env;
> + uint32_t hwcaps = 0;
> +
> + hwcaps |= ARM_HWCAP_ARM_SWP;
> + hwcaps |= ARM_HWCAP_ARM_HALF;
> + hwcaps |= ARM_HWCAP_ARM_THUMB;
> + hwcaps |= ARM_HWCAP_ARM_FAST_MULT;
> + hwcaps |= ARM_HWCAP_ARM_FPA;
> +
> + /* prove for the extra features */
probe?
> +#define GET_FEATURE(feat, hwcap) \
> + do {if (arm_feature(e, feat)) { hwcaps |= hwcap; } } while (0)
This doesn't return anything, it sets the hwcap flag. SET_HWCAP maybe?
> + 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_VFP_FP16, ARM_HWCAP_ARM_VFPv3D16);
I'm wondering if this translation table were better placed in
target-arm/helper.c where we fiddle with the features in the first
place. We could loop through all features here and call a function that
returns the hwcap or 0 and |= it. Me and others will be adding new
features and we'll risk adapting this here.
I was told that VFP_FP16 is *not* VFPv3-D16. Please remove that for now.
> +#undef GET_FEATURE
> +
> + return hwcaps;
> +}
>
> #endif
>
Andreas
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