Re: [PATCH 1/2] UEFI arm64: add noefi boot param

Will Deacon
2014-08-06T12:40:41Z

On Wed, Aug 06, 2014 at 09:38:25AM +0100, Dave Young wrote:
> Adding a noefi boot param like in X86 to disable efi runtime services support.
>
> This will be useful for debugging uefi problems. Also it will be useful
> for later kexec/kdump work. Kexec on uefi support in X86 depends on a fixed vm
> area specific for uefi runtime 1:1 mapping, kernel will switch to a different
> page table for any uefi runtime callback in virtual mode. In arm64 similar
> work probably is necessary. But kexec boot will just works with 'noefi' with
> the limitaion of lacking runtime services. The runtime services is not critical
> for kdump kernel for now. So as for kexec/kdump just leave the 1:1 mapping a
> future work.
>
> Signed-off-by: Dave Young <dyoung@redhat.com>

This looks fine to me, but I'd like Leif's ack before I merge it. Leif?

Will

> ---
> arch/arm64/kernel/efi.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> Index: linux-2.6/arch/arm64/kernel/efi.c
> ===================================================================
> --- linux-2.6.orig/arch/arm64/kernel/efi.c
> +++ linux-2.6/arch/arm64/kernel/efi.c
> @@ -31,6 +31,14 @@ static efi_runtime_services_t *runtime;
>
> static u64 efi_system_table;
>
> +static bool disable_runtime __initdata = false;
> +static int __init setup_noefi(char *arg)
> +{
> + disable_runtime = true;
> + return 0;
> +}
> +early_param("noefi", setup_noefi);
> +
> static int uefi_debug __initdata;
> static int __init uefi_debug_setup(char *str)
> {
> @@ -391,11 +399,14 @@ static int __init arm64_enter_virtual_mo
> return -1;
> }
>
> - pr_info("Remapping and enabling EFI services.\n");
> -
> - /* replace early memmap mapping with permanent mapping */
> mapsize = memmap.map_end - memmap.map;
> early_memunmap(memmap.map, mapsize);
> +
> + if (disable_runtime)
> + return -ENODEV;
> +
> + pr_info("Remapping and enabling EFI services.\n");
> + /* replace early memmap mapping with permanent mapping */
> memmap.map = (__force void *)ioremap_cache((phys_addr_t)memmap.phys_map,
> mapsize);
> memmap.map_end = memmap.map + mapsize;
>