Re: [PATCH] x86/efi: autoload efivars

[Matt Fleming <matt-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org>]

On Tue, 08 Jul, at 11:00:58AM, Lee, Chun-Yi wrote:
> The original patch is from Ben Hutchings's contribution to debian
> kernel. Got Ben's permission to remove the code of efi-pstore.c and
> then patch to linux-efi:
> https://github.com/BlankOn/linux-debian/blob/master/debian/patches/features/all/efi-autoload-efivars.patch
> 
> efivars is generally useful to have on EFI systems, and in some cases
> it may be impossible to load it after a kernel upgrade in order to
> complete a boot loader update. At the same time we don't want to waste
> memory on non-EFI systems by making them built-in.
> 
> Instead, give them module aliases as if they are platform drivers, and
> register a corresponding platform device whenever EFI runtime services
> are available.  This should trigger udev to load them.
> 
> Cc: Ben Hutchings <ben-/+tVBieCtBitmTQ+vhA3Yw@public.gmane.org>
> Cc: Matt Fleming <matt.fleming-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> Signed-off-by: Lee, Chun-Yi <jlee-IBi9RG/b67k@public.gmane.org>
> ---
>  arch/x86/platform/efi/efi.c    | 15 +++++++++++++++
>  drivers/firmware/efi/efivars.c |  1 +
>  2 files changed, 16 insertions(+)
> 
> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> index 87fc96b..c295c08 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -44,6 +44,7 @@
>  #include <linux/io.h>
>  #include <linux/reboot.h>
>  #include <linux/bcd.h>
> +#include <linux/platform_device.h>
>  
>  #include <asm/setup.h>
>  #include <asm/efi.h>
> @@ -780,6 +781,20 @@ void __init efi_late_init(void)
>  	efi_bgrt_init();
>  }
>  
> +#ifdef CONFIG_EFI_VARS_MODULE
> +static int __init efi_load_efivars(void)
> +{
> +	struct platform_device *pdev;
> +
> +	if (!efi_enabled(EFI_RUNTIME_SERVICES))
> +		return 0;
> +
> +	pdev = platform_device_register_simple("efivars", 0, NULL, 0);
> +	return IS_ERR(pdev) ? PTR_ERR(pdev) : 0;
> +}
> +device_initcall(efi_load_efivars);
> +#endif
> +

Could this be moved to drivers/firmware/efi/efi.c? That way the arm64
folks could benefit from it too.

>  void __init efi_set_executable(efi_memory_desc_t *md, bool executable)
>  {
>  	u64 addr, npages;
> diff --git a/drivers/firmware/efi/efivars.c b/drivers/firmware/efi/efivars.c
> index 463c565..f256ecd 100644
> --- a/drivers/firmware/efi/efivars.c
> +++ b/drivers/firmware/efi/efivars.c
> @@ -78,6 +78,7 @@ MODULE_AUTHOR("Matt Domsch <Matt_Domsch-DYMqY+WieiM@public.gmane.org>");
>  MODULE_DESCRIPTION("sysfs interface to EFI Variables");
>  MODULE_LICENSE("GPL");
>  MODULE_VERSION(EFIVARS_VERSION);
> +MODULE_ALIAS("platform:efivars");
>  
>  LIST_HEAD(efivar_sysfs_list);
>  EXPORT_SYMBOL_GPL(efivar_sysfs_list);
> -- 
> 1.8.4.5
> 
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-- 
Matt Fleming, Intel Open Source Technology Center