linux-kernel - Re: [PATCH 6/6] x86: fixes some bugs about EFI memory map handling

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Date:	Fri, 25 Jan 2008 17:40:15 +0800
From:	"Huang, Ying" <ying.huang@...el.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>, Andi Kleen <ak@...e.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/6] x86: fixes some bugs about EFI memory map handling

On Fri, 2008-01-25 at 10:31 +0100, Ingo Molnar wrote:
> * Huang, Ying <ying.huang@...el.com> wrote:
> 
> > This patch fixes some bugs of EFI memory handing code.
> > 
> > - On x86_64, it is possible that EFI memory map can not be mapped via
> >   identity map, so efi_map_memmap is removed, just use early_ioremap.
> > 
> > - On i386, the EFI memory map mapping take effect cross paging_init,
> >   so it is not necessary to use efi_map_memmap.
> > 
> > - EFI memory map is unmapped in efi_enter_virtual_mode to avoid
> >   early_ioremap leak.
> 
> thanks, applied.
> 
> btw., it would be nice to consolidate this some more. Why is there a 
> separate efi_ioremap(), which is mapped to ioremap() on 32-bit, and 
> which is mapped to a fixmap based special mapper on 64-bit?
> 
> To me it appears this wants to be ioremap() on both 64-bit and 32-bit, 
> and we could remove efi_ioremap() altogether. Hm?

To support kexec, I want to map the EFI memory area on same virtual
address on different boot of different version of kernel. Then, the EFI
runtime service will always get the same execution environment. This is
because a weakness of EFI runtime service, it can not reset its
execution environment, except reboot.

Best Regards,
Huang Ying
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