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

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Date:	Fri, 25 Jan 2008 10:50:18 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	"Huang, Ying" <ying.huang@...el.com>
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


* Huang, Ying <ying.huang@...el.com> wrote:

> 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.

so this basically means that on 32-bit kexec wont work right - i.e. only 
64-bit has been enhanced this way? What am i missing?

	Ingo
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