Re: [PATCH 0/2] arm64: support initrd outside of mapped RAM

[Mark Salter <msalter@redhat.com>]

On Tue, 2015-07-28 at 15:59 +0100, Mark Rutland wrote:
> Hi Mark,
> 
> As a heads-up, it looks like you missed a space when sending this; Arnd
> and Ard got merged into:
> 
> "Arnd Bergmann <arnd@arndb.de>--cc=Ard Biesheuvel" <
> ard.biesheuvel@linaro.org>
> 
> I've corrected that for this reply.

Oops. Thanks.

> 
> On Tue, Jul 28, 2015 at 03:32:39PM +0100, Mark Salter wrote:
> > When booting an arm64 kernel w/initrd using UEFI/grub, use of mem= will 
> > likely
> > cut off part or all of the initrd. This leaves it outside the kernel 
> > linear
> > map which leads to failure when unpacking. The x86 code has a similar 
> > need to
> > relocate an initrd outside of mapped memory in some cases.
> > 
> > The current x86 code uses early_memremap() to copy the original initrd 
> > from
> > unmapped to mapped RAM. This patchset creates a generic 
> > copy_from_early_mem()
> > utility based on that x86 code and has arm64 use it to relocate the 
> > initrd
> > if necessary.
> 
> This sounds like a sane idea to me.
> 
> > Mark Salter (2):
> >   mm: add utility for early copy from unmapped ram
> >   arm64: support initrd outside kernel linear map
> > 
> >  arch/arm64/kernel/setup.c           | 55 
> > +++++++++++++++++++++++++++++++++++++
> >  include/asm-generic/early_ioremap.h |  6 ++++
> >  mm/early_ioremap.c                  | 22 +++++++++++++++
> >  3 files changed, 83 insertions(+)
> 
> Any reason for not moving x86 over to the new generic version?

I have a patch to do that but I'm not sure how to contrive a
testcase to exercise it.

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