Commit Graph

5 Commits

Author SHA1 Message Date
Grant Erickson
5907630ffc powerpc/40x: Limit allocable DRAM during early mapping
If the size of DRAM is not an exact power of two, we may not have
covered DRAM in its entirety with large 16 and 4 MiB pages.  If that
is the case, we can get non-recoverable page faults when doing the
final PTE mappings for the non-large page PTEs.

Consequently, we restrict the top end of DRAM currently allocable
by updating '__initial_memory_limit_addr' so that calls to the LMB to
allocate PTEs for "tail" coverage with normal-sized pages (or other
reasons) do not attempt to allocate outside the allowed range.

Signed-off-by: Grant Erickson <gerickson@nuovations.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
2008-11-13 10:10:56 -05:00
Kumar Gala
99c62dd773 [POWERPC] Remove and replace uses of PPC_MEMSTART with memstart_addr
A number of users of PPC_MEMSTART (40x, ppc_mmu_32) can just always
use 0 as we don't support booting these kernels at non-zero physical
addresses since their exception vectors must be at 0 (or 0xfffx_xxxx).

For the sub-arches that support relocatable interrupt vectors
(book-e), it's reasonable to have memory start at a non-zero physical
address.  For those cases use the variable memstart_addr instead of
the #define PPC_MEMSTART since the only uses of PPC_MEMSTART are for
initialization and in the future we can set memstart_addr at runtime
to have a relocatable kernel.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-04-17 07:46:12 +10:00
Grant Likely
bd942ba3db [POWERPC] ppc405 Fix arithmatic rollover bug when memory size under 16M
mmu_mapin_ram() loops over total_lowmem to setup page tables.  However, if
total_lowmem is less that 16M, the subtraction rolls over and results in
a number just under 4G (because total_lowmem is an unsigned value).

This patch rejigs the loop from countup to countdown to eliminate the
bug.

Special thanks to Magnus Hjorth who wrote the original patch to fix this
bug.  This patch improves on his by making the loop code simpler (which
also eliminates the possibility of another rollover at the high end)
and also applies the change to arch/powerpc.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
2007-11-01 07:15:59 -05:00
Josh Boyer
4d922c8dc3 [POWERPC] 40x MMU
Add MMU definitions for 40x platforms.  Also fixes two warnings in 40x_mmu.c.

Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
2007-08-20 07:28:48 -05:00
Josh Boyer
15f6527e8e [POWERPC] Rename 4xx paths to 40x
4xx is a bit of a misnomer for certain things, as they really apply to PowerPC
40x only.  Rename some of the files to clean this up.

Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
2007-08-20 07:27:07 -05:00