Re: [PATCH -mm 0/3] i386 boot: replace boot_ioremap with enhanced bt_ioremap

[Ingo Molnar <mingo@elte.hu>]

* H. Peter Anvin <hpa@zytor.com> wrote:

> I did a quick scan over the patchset (not quite awake yet, so I may 
> very well have missed something), but it looks like EFI (again!) is 
> the only user of ioremapping before paging_init().  This makes me 
> wonder if that code can't be restructured so that isn't necessary.

i think that in general making access to unmapped memory a bit easier is 
generally a good robustness idea as ACPI could be impacted by it as 
well.

Fundamentally, paging_init() has obvious dependency on "figuring out the 
memory setup" of the box, and "figuring out the memory setup" means 
interpreting various data structures passed in by the BIOS - some of 
which might be in not yet mapped areas or iommu areas (if we have to do 
some early quirk). So having a robust implementation of ioremap_early() 
sounds like a definitive plus.

	Ingo