[PATCH 3/3] at91: make PLAT_PHYS_OFFSET depending on !ARM_PATCH_PHYS_VIRT or XIP_KERNEL
Russell King - ARM Linux
linux at arm.linux.org.uk
Mon May 2 19:09:40 EDT 2011
On Tue, May 03, 2011 at 12:50:46AM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 23:52 Mon 02 May , Russell King - ARM Linux wrote:
> > Ideally, I'd like to see platforms not provide PLAT_PHYS_OFFSET.
> > However, there are two cases where it's needed by generic ARM code as
> > you've identified above.
> >
> > Does AT91 support XIP_KERNEL? It doesn't support XIP from flash (MTD_XIP)
> > so I suspect this isn't a particularly useful configuration.
>
> I never see a board using it
I think Nicolas questioned whether it was worth keeping XIP support in
the kernel - I suspect there are very few users of that.
We know that MTD_XIP is only used on OMAP1, PXA and SA1100 platforms.
Anyone else using XIP_KERNEL either has the kernel in some kind of ROM
or off-line updatable flash (while the kernel runs from it, this flash
would have to be read-only without MTD_XIP support.)
> > As far as ARM_PATCH_PHYS_VIRT, maybe AT91 should force this to always
> > be selected. That then means it can eliminate the PLAT_PHYS_OFFSET
> > definition entirely.
>
> I get this in mind too but as it's sleep mark EXPERIMANTAL I was not sure
> to enable it by default
It's marked experimental because it's a new feature which needs testing
to fully prove itself across all platforms. If you're happy that it
works for your class of platforms, then there shouldn't be much of a
problem.
SMP is also marked experimental, but has been around for a while now,
and the norm for some systems already. However, SMP has been around for
a while and can have that tag dropped now.
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