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 15:08:10 +0900
From:	Simon Horman <horms@...ge.net.au>
To:	Dave Young <dyoung@...hat.com>
Cc:	matt.fleming@...el.com, bp@...en8.de, linux-kernel@...r.kernel.org,
	linux-efi@...r.kernel.org, vgoyal@...hat.com
Subject: Re: [PATCH]x86 efi: do not export efi runtime map in case old map

On Fri, May 30, 2014 at 01:54:47PM +0800, Dave Young wrote:
> 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.

Thanks, I understand.

If the kernel side ends up being rejected or modified please
send an update for kexec-tools accordingly.

> 
> 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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