Re: [PATCHv3 08/11] arm64: Check for selected granule support

From	Jeremy Linton <jeremy.linton@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCHv3 08/11] arm64: Check for selected granule support
Date	2015-10-15 16:50 +0200
Message-ID	<qjS0V-Yf-5@gated-at.bofh.it> (permalink)
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On 10/15/2015 06:25 AM, Suzuki K. Poulose wrote:
> +	/*
> +	 * Check to see if the CPU supports the requested pagesize
> +	 */
> +	asm volatile("mrs %0, ID_AA64MMFR0_EL1" : "=r" (aa64mmfr0_el1));
> +	aa64mmfr0_el1 >>= ID_AA64MMFR0_TGRAN_SHIFT;
> +	if ((aa64mmfr0_el1 & 0xf) != ID_AA64MMFR0_TGRAN_SUPPORTED) {
> +		pr_efi_err(sys_table_arg, PAGE_SIZE_STR" granule not supported by the CPU\n");
> +		return EFI_UNSUPPORTED;
> +	}

This is definitely an improvement over my original hack job.

I would like to add, that I actually think this should be in a new 
function "check_kernel_compatibility" (or whatever) that is called 
before handle_kernel_image.

That is because I don't really think it belongs in handle_kernel_image 
which is focused on relocation. Plus, if you add another function, you 
can avoid the "Failed to relocate kernel" error that comes out following 
the granule not supported message. Further, checks like this in the 
future will have a place to live.

Of course you will then need a matching stubbed out function for the 
normal arm kernel as well.

Thanks,

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Thread

[PATCHv3 08/11] arm64: Check for selected granule support "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-10-14 13:30 +0200
  Re: [PATCHv3 08/11] arm64: Check for selected granule support Mark Rutland <mark.rutland@arm.com> - 2015-10-14 19:30 +0200
    Re: [PATCHv3 08/11] arm64: Check for selected granule support Mark Rutland <mark.rutland@arm.com> - 2015-10-14 19:40 +0200
    Re: [PATCHv3 08/11] arm64: Check for selected granule support "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-10-15 11:50 +0200
      Re: [PATCHv3 08/11] arm64: Check for selected granule support Mark Rutland <mark.rutland@arm.com> - 2015-10-15 12:40 +0200
  Re: [PATCHv3 08/11] arm64: Check for selected granule support Jeremy Linton <jeremy.linton@arm.com> - 2015-10-14 23:20 +0200
    Re: [PATCHv3 08/11] arm64: Check for selected granule support "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-10-15 11:50 +0200
    Re: [PATCHv3 08/11] arm64: Check for selected granule support Mark Rutland <mark.rutland@arm.com> - 2015-10-15 12:50 +0200
      Re: [PATCHv3 08/11] arm64: Check for selected granule support "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-10-15 13:30 +0200
        Re: [PATCHv3 08/11] arm64: Check for selected granule support Mark Rutland <mark.rutland@arm.com> - 2015-10-15 14:40 +0200
          Re: [PATCHv3 08/11] arm64: Check for selected granule support "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-10-15 15:00 +0200
            Re: [PATCHv3 08/11] arm64: Check for selected granule support Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-10-16 10:10 +0200
        Re: [PATCHv3 08/11] arm64: Check for selected granule support Jeremy Linton <jeremy.linton@arm.com> - 2015-10-15 16:50 +0200
          Re: [PATCHv3 08/11] arm64: Check for selected granule support "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-10-15 17:10 +0200
          Re: [PATCHv3 08/11] arm64: Check for selected granule support Mark Rutland <mark.rutland@arm.com> - 2015-10-15 17:20 +0200
            Re: [PATCHv3 08/11] arm64: Check for selected granule support Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-10-16 10:20 +0200

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