Re: [PATCH] arm64: allow late use of early_ioremap

[Hanjun Guo]

Hi Mark,

On 2015å01æ13æ 03:09, Mark Salter wrote:
> On Mon, 2015-01-12 at 17:25 +0000, Will Deacon wrote:
> > On Mon, Jan 12, 2015 at 04:55:11PM +0000, Mark Salter wrote:
> > > Commit 0e63ea48b4d8 (arm64/efi: add missing call to early_ioremap_reset())
> > > added a missing call to early_ioremap_reset(). This triggers a BUG if code
> > > tries using early_ioremap() after the early_ioremap_reset(). This is a
> > > problem for some ACPI code which needs short-lived temporary mappings
> > > after paging_init() but before mm_init(). This patch adds definitions for

Minor update:
... after paging_init() but before acpi_early_init() in start_kernel().

In ACPI, permanent mapping will be used after acpi_gbl_permanent_mmap
set to 1 in acpi_early_init(), since GIC init and Arch timer init will
be called before acpi_early_init(), early_ioremap() is still needed
after mm_init().

> > > the __late_set_fixmap() and __late_clear_fixmap() which avoids the BUG
> > > by allowing later use of early_ioremap().
> > >
> > > Signed-off-by: Mark Salter <msalter@xxxxxxxxxx>
> > > CC: Leif Lindholm <leif.lindholm@xxxxxxxxxx>
> > > CC: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> > > ---
> > >   arch/arm64/include/asm/fixmap.h | 3 +++
> > >   1 file changed, 3 insertions(+)
> >
> > Given that we don't support ACPI on arm64 in mainline, I assume this can
> > wait until at least 3.20?
>
> Sure. Just needs it to go in before ACPI code. And tbh, the ACPI code
> could change and make this unneeded.

This is the best solution for now, so I need to add this patch as the 
first one for ACPI core patch set, is it ok for you?

Thanks
Hanjun
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