Messages in this thread | | | Date | Thu, 15 Oct 2015 16:11:14 +0100 | From | Mark Rutland <> | Subject | Re: [PATCHv3 08/11] arm64: Check for selected granule support |
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On Thu, Oct 15, 2015 at 09:47:53AM -0500, Jeremy Linton wrote: > 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.
To bikeshed, perhaps efi_arch_check_system?
> 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.
I agree.
There are some other diagnostic utilities I'd like to add to the stub (e.g. dumping the memory map and ID registers) that would help with diagnosing boot issues. I started on those at Connect, but realised I needed to first implement half of printf for those to be useful.
> Of course you will then need a matching stubbed out function for the > normal arm kernel as well.
I'm sure there are similar things we'll want to check for 32-bit (e.g. LPAE support), but a stub should be fine for now.
Thanks, Mark.
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