"Linuxppc-dev"Yes we could do a more elaborated modification in the future. However it also has an impact on the boot loader, so I'm not sure we should make it the default without thinking twice.
<linuxppc-dev-bounces+joakim.tjernlund=transmode.se@xxxxxxxxxxxxxxxx>
wrote on 2013/10/11 14:56:40:
Activating CONFIG_PIN_TLB allows access to the 24 first Mbytes of memoryatbootup instead of 8. It is needed for "big" kernels for instance whenactivatingCONFIG_LOCKDEP_SUPPORT. This needs to be taken into account in init_32too,otherwise memory allocation soon fails after startup.linux-3.11/arch/powerpc/kernel/head_8xx.S
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
diff -ur linux-3.11.org/arch/powerpc/kernel/head_8xx.S--- linux-3.11.org/arch/powerpc/mm/init_32.c 2013-09-0222:46:10.000000000 +0200+++ linux-3.11/arch/powerpc/mm/init_32.c 2013-09-09 11:28:54.000000000+0200@@ -213,7 +213,12 @@0x01800000));
*/
BUG_ON(first_memblock_base != 0);
+#ifdef CONFIG_PIN_TLB
+ /* 8xx can only access 24MB at the moment */
+ memblock_set_current_limit(min_t(u64, first_memblock_size,
+#else0x00800000));
/* 8xx can only access 8MB at the moment */
memblock_set_current_limit(min_t(u64, first_memblock_size,
+#endifhmm, I think you should always map 24 MB (or less if RAM < 24 MB) and do
}
#endif /* CONFIG_8xx */
the same
in head_8xx.S.
Or to keep it simple, just always map at least 16 MB here and in
head_8xx.S, assuming
that 16 MB is min RAM for any 8xx system running 3.x kernels.
Christophe
Much of the need for pinning would go away if you adopted my 8MB pages
from 2.4 to 3.x
Jocke