linux-kernel - Re: [PATCH] Fix e820 end address with EFI

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Message-Id: <1235960708.6204.176.camel@yhuang-dev.sh.intel.com>
Date:	Mon, 02 Mar 2009 10:25:08 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Brian Maly <bmaly@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Fix e820 end address with EFI

On Mon, 2009-03-02 at 10:16 +0800, Yinghai Lu wrote:
> Huang Ying wrote:
> > On Mon, 2009-03-02 at 09:39 +0800, Brian Maly wrote:
> >> Huang Ying wrote: 
> >>> Hi, Brian,
> >>>
> >>> On Mon, 2009-03-02 at 04:13 +0800, Brian Maly wrote:
> >>>   
> >>>> I was able verify the kernel that does not boot on the MacBook (vanilla 
> >>>> 2.6.29-rc4) does call efi_ioremap() which bails out early returning 
> >>>> NULL. So no remapping happens in this case.  I have no idea if 
> >>>> efi_ioremap ever does succeed in mapping any ranges though being I have 
> >>>> no video or console this early in the boot and have to rely on triple 
> >>>> faulting as a means of debugging.
> >>>>     
> >>> Please attach your dmesg of successful boot, so we can take a look at
> >>> the EFI memory map.
> >>>
> >>> Best Regards,
> >>> Huang Ying
> >>>   
> >> This dmesg is from a 2.6.25 kernel which works fine. I can gather
> >> other debugging info from the booting kernels if needed. But its a
> >> challenge to debug the bad kernel being efifb is initialized very late
> >> (so you never even get to the video initialization and cant see any
> >> logged messages) and since its a MacBook I dont have a real serial
> >> port for serial console. The efi map is for MacBook has a different
> >> layout from other EFI systems I have to test on. 2.6.29 kernel works
> >> on every EFI system I have except MacBook.
> > 
> > It seems that you have an EFI system which has too big runtime area.
> > 
> > EFI: mem44: type=0, attr=0x8000000000000000, range=[0x000000007ff00000-0x0000000080000000) (1MB)
> > 
> > efi_ioremap() can map only memory range < 400k now.
> > 
> > It seems that efi_ioremap is the bottle net now. Can we just use
> > init_memory_mapping() instead of efi_ioremap() for EFI runtime area?
> > 
> > Yinghai, how about your opinion?
> 
> you could call init_memory_maping() in that efi_ioremap position?
> 
> problems is how about 32bit?

efi_ioremap() is defined as ioremap_cache() on 32bit system. As that in
arch/x86/include/asm/efi.h.

On 64bit system, efi_ioremap() can be a wrapper for
init_memory_mapping(). Do you think it is appropriate?

Best Regards,
Huang Ying

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