linux-kernel - Re: [PATCH]x86 efi: do not export efi runtime map in case old map

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Date:	Fri, 30 May 2014 13:54:47 +0800
From:	Dave Young <dyoung@...hat.com>
To:	matt.fleming@...el.com, bp@...en8.de, linux-kernel@...r.kernel.org,
	linux-efi@...r.kernel.org, vgoyal@...hat.com, horms@...ge.net.au
Subject: Re: [PATCH]x86 efi: do not export efi runtime map in case old map

Ccing Simon.

Simon, appologize for not ccing you about this kernel patch. I see you have
applied the userspace patch for checking sysfs runtime existance.

The userspace patch depends on this patch but it is not harmful even without
this kernel patch. So applying the userspace patch before this one is still
safe.

On 05/30/14 at 11:20am, Dave Young wrote:
> 
> For ioremapped efi memory aka old_map the virt addresses are not persistant
> across kexec reboot. kexec-tools will read the runtime maps from sysfs then
> pass them to 2nd kernel and assuming kexec efi boot is ok. This will cause
> kexec boot failure.
> 
> To address this issue do not export runtime maps in case efi old_map so
> userspace can use no efi boot instead.
> 
> Signed-off-by: Dave Young <dyoung@...hat.com>
> ---
>  arch/x86/platform/efi/efi.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> index 3781dd3..4d36932 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -919,6 +919,9 @@ static void __init save_runtime_map(void)
>  	void *tmp, *p, *q = NULL;
>  	int count = 0;
>  
> +	if (efi_enabled(EFI_OLD_MEMMAP))
> +		return;
> +
>  	for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
>  		md = p;
>  
> -- 
> 1.8.3.1
> 
> --
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