linux-kernel - Re: [PATCH V7 4/5] arm64: apei: implement arch_apei_get_mem

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Date:	Mon, 27 Jul 2015 10:54:51 +0100
From:	Matt Fleming <matt.fleming@...el.com>
To:	Will Deacon <will.deacon@....com>
CC:	Catalin Marinas <Catalin.Marinas@....com>,
	"Jonathan (Zhixiong) Zhang" <zjzhang@...eaurora.org>,
	"fu.wei@...aro.org" <fu.wei@...aro.org>,
	"al.stone@...aro.org" <al.stone@...aro.org>,
	"rjw@...ysocki.net" <rjw@...ysocki.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>
Subject: Re: [PATCH V7 4/5] arm64: apei: implement
 arch_apei_get_mem_attributes()

On Mon, 2015-07-27 at 10:45 +0100, Will Deacon wrote:
> 
> That bit's fine. The weird bit is:
> 
>   pgprot_t prot;
> 
>   prot = efi_mem_attributes(addr);
> 
> Since that's putting the arch-independent format into the pg_prot.

Oops, missed that. Yeah that's funky.

> > I don't see how you can do that any other way than by using pgprot_t.
> > 
> > Really, the problem here is that ioremap_page_caller() has no notion of
> > "map this range in a firmware-compatible manner". If we could do, for
> > example,
> > 
> > 	ioremap_page_range(vaddr, vend, paddr, PAGE_FW_COMPAT);
> > 
> > that would allow the innards of the arch-ioremap to figure out exactly
> > how to map this range so that the firmware could access it coherently.
> > 
> > I suggested this previously but it didn't gain any traction.
> 
> Yeah, or just ioremap_efi.
> 
> </me runs away>

Someone beat you to it ;-)

arch/x86/include/asm/efi.h:#define efi_ioremap(addr, size, type, attr)	ioremap_cache(addr, size)
arch/x86/include/asm/efi.h:extern void __iomem *__init efi_ioremap(unsigned long addr, unsigned long size,
arch/x86/platform/efi/efi.c:		va = efi_ioremap(md->phys_addr, size,
arch/x86/platform/efi/efi_64.c:void __iomem *__init efi_ioremap(unsigned long phys_addr, unsigned long size,
arch/x86/platform/efi/efi_64.c:		efi_ioremap(top, size - (top - phys_addr), type, attribute);


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