linux-kernel - Re: [PATCH v4 1/5] efi: Introduce EFI

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Message-ID: <20140519204657.GB3529@olila.local.net-space.pl>
Date:	Mon, 19 May 2014 22:46:57 +0200
From:	Daniel Kiper <daniel.kiper@...cle.com>
To:	Jan Beulich <JBeulich@...e.com>
Cc:	david.vrabel@...rix.com, ian.campbell@...rix.com,
	stefano.stabellini@...citrix.com, jeremy@...p.org,
	matt.fleming@...el.com, x86@...nel.org, tglx@...utronix.de,
	xen-devel@...ts.xenproject.org, boris.ostrovsky@...cle.com,
	konrad.wilk@...cle.com, eshelton@...ox.com, mingo@...hat.com,
	mjg59@...f.ucam.org, linux-efi@...r.kernel.org,
	linux-kernel@...r.kernel.org, hpa@...or.com
Subject: Re: [PATCH v4 1/5] efi: Introduce EFI_DIRECT flag

On Mon, May 19, 2014 at 02:30:45PM +0100, Jan Beulich wrote:
> >>> On 16.05.14 at 22:41, <daniel.kiper@...cle.com> wrote:
> > @@ -457,6 +460,21 @@ void __init efi_free_boot_services(void)
> >  	efi_unmap_memmap();
> >  }
> >
> > +static void __init __iomem *efi_early_ioremap(resource_size_t phys_addr,
> > +							unsigned long size)
> > +{
> > +	if (efi_enabled(EFI_DIRECT))
> > +		return early_ioremap(phys_addr, size);
> > +
> > +	return (__force void __iomem *)phys_addr;
>
> Now that surely needs some explanation: I can't see how this can
> ever be correct, Xen or not being completely irrelevant.

I hope that efi_enabled(EFI_DIRECT) is obvious. However, in case of
!efi_enabled(EFI_DIRECT) some structures are created artificially
and they live in virtual address space. So that is why they should
not be mapped. If you wish I could add relevant comment here.

Daniel
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