On Fri, May 30, 2014 at 04:33:46PM +0100, Rob Herring wrote:

On Tue, Apr 15, 2014 at 6:06 AM, Liu Hua [off-list ref] wrote:

quoted

In 32-bit ARM systems, the fixmap mapping region can support
no more than 14 CPUs(total: 896k; one CPU: 64K). And we can
configure NR_CPUS up to 32. So there is a mismatch.

This patch moves fixmapping region downwards to region
0xffc00000-0xffe00000. Then the fixmap mapping region can
support up to 32 CPUs

Ugg, this series breaks using fixmap for anything other than kmap
since 32 cpus requires all 2MB of the region and nothing is left.
There's work in flight to support early_ioremap, early console, and RO
text patching which all use the fixmap region.

There's a couple of options to solve this:

- Only support up to 16 cpus. It could be anywhere between 17-31, but
that seems somewhat unlikely. Are we really ever going to see 32-bit
32 core systems?

I'd be fine with restricting the limit to 16 CPUs.

Will