linux-kernel - Re: [RFC PATCH] x86: make 64bit efi to use ioremap_cache for efi

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Message-ID: <86802c440810051104o44f7a3bbu6b37d7727be46772@mail.gmail.com>
Date:	Sun, 5 Oct 2008 11:04:35 -0700
From:	"Yinghai Lu" <yinghai@...nel.org>
To:	"huang ying" <huang.ying.caritas@...il.com>
Cc:	"Ingo Molnar" <mingo@...e.hu>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Huang Ying" <ying.huang@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] x86: make 64bit efi to use ioremap_cache for efi_ioremap

On Sun, Oct 5, 2008 at 1:56 AM, huang ying <huang.ying.caritas@...il.com> wrote:
> On Sun, Oct 5, 2008 at 1:44 AM, Yinghai Lu <yinghai@...nel.org> wrote:
>> On Sat, Oct 4, 2008 at 2:35 AM, huang ying <huang.ying.caritas@...il.com> wrote:
> [...]
>>> Using __va and efi_ioremap() here is to make EFI support compatible
>>> with kexec. Because EFI provide only efi_enter_virtual_mode(), no
>>> efi_leave_virtual_mode(), we should make EFI runtime memory area
>>> mapped to same virtual memory area in original kernel and kexeced
>>> kernel, so that the EFI runtime services can be used in kexeced
>>> kernel.
>>
>> so need to make efi range all under direct-mapping like E820-RAM?
>
> Some EFI runtime range is just some RAM area used by EFI runtime
> services, they can be direct-mapped. Some EFI runtime range may be IO
> MEM range used by EFI runtime services, it is possible that these IO
> MEM range can not be direct-mapped. So I implement efi_ioremap() to
> deal with them.
>

i'm confused.

so
--- linux-2.6.orig/arch/x86/kernel/efi.c
+++ linux-2.6/arch/x86/kernel/efi.c
@@ -475,10 +475,7 @@ void __init efi_enter_virtual_mode(void)
               size = md->num_pages << EFI_PAGE_SHIFT;
               end = md->phys_addr + size;

-               if (PFN_UP(end) <= max_low_pfn_mapped)
-                       va = __va(md->phys_addr);
-               else
-                       va = efi_ioremap(md->phys_addr, size);
+               va = efi_ioremap(md->phys_addr, size);

               md->virt_addr = (u64) (unsigned long) va;
should be ok.

then how about use ioremap directly to replace fixed mapping in 64bit
with efi_ioremap?

YH
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