linux-kernel - Re: [PATCH] EFI: Do not use __pa() to get the physical address of an ioremapped memory range

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Message-ID: <1314880125.8038.39.camel@mfleming-mobl1.ger.corp.intel.com>
Date:	Thu, 01 Sep 2011 13:28:45 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Zhang Rui <rui.zhang@...el.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Matthew Garrett <mjg59@...f.ucam.org>
Subject: Re: [PATCH] EFI: Do not use __pa() to get the physical address of
 an ioremapped memory range

On Thu, 2011-09-01 at 16:14 +0800, Zhang Rui wrote:
> On Thu, 2011-09-01 at 14:55 +0800, Zhang, Rui wrote: 
> > From: Zhang Rui <rui.zhang@...el.com>
> > Date: Wed, 31 Aug 2011 09:59:01 +0800
> > Subject: Do not use __pa() to get the physical address of an ioremapped memory range.
> > 
> > set_memory_uc uses __pa() to translate the virtual address to the physical address.
> > This breaks a EFI_MEMORY_MAPPED_IO memory region in my case as it was ioremapped first.
> > 
> oops, wrong patch was attached.
> 
> here is the correct patch.
> 
> From: Zhang Rui <rui.zhang@...el.com>
> Date: Wed, 31 Aug 2011 09:59:01 +0800
> Subject: Do not use __pa() to get the physical address of an ioremapped memory range.
> 
> set_memory_uc uses __pa() to translate the virtual address to the physical address.
> This breaks a EFI_MEMORY_MAPPED_IO memory region in my case as it was ioremapped first.

Hmm.. does anyone know why we ioremap_cache() the memory on
CONFIG_X86_32 instead of ioremap_nocache()? In the case of
EFI_MEMORY_MAPPED_IO the memory really needs to be uncached. Then if
we've ioremap'd the memory we should skip set_memory_uc() altogether,
no?

-- 
Matt Fleming, Intel Open Source Technology Center

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