RE: [PATCH -mm 0/3] i386 boot: replace boot_ioremap with enhancedbt_ioremap

From: Pallipadi, Venkatesh
Date: Tue Jan 15 2008 - 21:50:40 EST




>-----Original Message-----
>From: Huang, Ying
>Sent: Tuesday, January 15, 2008 1:49 AM
>To: Ingo Molnar; Pallipadi, Venkatesh
>Cc: akpm@xxxxxxxxxxxxxxxxxxxx; H. Peter Anvin; Thomas
>Gleixner; Ingo Molnar; Andi Kleen; linux-kernel@xxxxxxxxxxxxxxx
>Subject: Re: [PATCH -mm 0/3] i386 boot: replace boot_ioremap
>with enhancedbt_ioremap
>
>On Tue, 2008-01-15 at 09:44 +0100, Ingo Molnar wrote:
>> * Huang, Ying <ying.huang@xxxxxxxxx> wrote:
>>
>> > This patchset replaces boot_ioremap with a enhanced version of
>> > bt_ioremap and renames the bt_ioremap to early_ioremap.
>This reduces
>> > 12k from .init.data segment and increases the size of
>memory that can
>> > be re-mapped before paging_init to 64k.
>>
>> in latest x86.git#mm there's an early_ioremap() introduced
>as part of
>> the PAT series - available on both 32-bit and 64-bit. Could
>you take a
>> look at it and use that if it's OK for your purposes?
>
>After checking the early_ioremap() implementation in
>arch/x86/kernel/setup_32.c, I found that it is a duplication of
>bt_ioremap() implementation in arch/x86/mm/ioremap_32.c. Both
>implementations use set_fixmap(), so they can be used only after
>paging_init().
>
>The early_ioremap implementation provided in this patchset works as
>follow:
>
>- Enhances bt_ioremap, make it usable before paging_init() via a
>dedicated PTE page.
>- Rename bt_ioremap to early_ioremap
>
>So I think maybe we should replace the early_ioremap()
>implementation in
>PAT series with that of this series.
>

Agreed. PAT can use this for early mappings. Thanks for the patches :)

-Venki
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