Re: [PATCH v2 05/25] powerpc/8xx: Fix vaddr for IMMR early remap

On Tue, Sep 22, 2015 at 06:50:38PM +0200, Christophe Leroy wrote:

Memory: 124428K/131072K available (3748K kernel code, 188K rwdata,
648K rodata, 508K init, 290K bss, 6644K reserved)
Kernel virtual memory layout:
  * 0xfffdf000..0xfffff000  : fixmap
  * 0xfde00000..0xfe000000  : consistent mem
  * 0xfddf6000..0xfde00000  : early ioremap
  * 0xc9000000..0xfddf6000  : vmalloc & ioremap
SLUB: HWalign=16, Order=0-3, MinObjects=0, CPUs=1, Nodes=1

Mapping IMMR 1:1 is just wrong because it may overlap with another
area. On most mpc8xx boards it is OK because IMMR is set to
0xff000000 but for instance on EP88xC board, IMMR is at 0xfa200000
which overlaps with VM ioremap area

This patch fixes the virtual address for remapping IMMR to 0xff000000,
regardless of the value of IMMR.

The size of IMMR area is 256kbytes (CPM at offset 0, security engine
at offset 128) so 512kbytes is enough and allows to handle the EP88xC
case (which is not 8Mbytes but only 2Mbytes aligned) the same way.

Signed-off-by: Christophe Leroy <redacted>

Instead of hardcoding 0xff000000, can you use asm/fixmap.h to allocate a
virtual address at compile time?

-Scott