Depending on the number of available BATs for mapping the different
kernel areas, it might be needed to increase the alignment of _etext
and/or of data areas.
This patchs allows the user to do it via Kconfig.
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
arch/powerpc/Kconfig | 32 ++++++++++++++++++++++++++++++--
1 file changed, 30 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 1828fefd99f9..3f6365f29c65 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -731,16 +731,44 @@ config THREAD_SHIFT
Used to define the stack size. The default is almost always what you
want. Only change this if you know what you are doing.
+config ETEXT_SHIFT_BOOL
+ bool "Set custom etext alignment" if STRICT_KERNEL_RWX && PPC_BOOK3S_32
+ depends on ADVANCED_OPTIONS
+ help
+ This option allows you to set the kernel end of text alignment. When
+ RAM is mapped by blocks, the alignment needs to fit the size and
+ number of possible blocks. The default should be OK for most configs.
+
+ Say N here unless you know what you are doing.
+
config ETEXT_SHIFT
- int
+ int "_etext shift" if ETEXT_SHIFT_BOOL
+ range 17 28 if STRICT_KERNEL_RWX && PPC_BOOK3S_32
default 17 if STRICT_KERNEL_RWX && PPC_BOOK3S_32
default PPC_PAGE_SHIFT
+ help
+ On Book3S 32 (603+), IBATs are used to map kernel text.
+ Smaller is the alignment, greater is the number of necessary IBATs.
+
+config DATA_SHIFT_BOOL
+ bool "Set custom data alignment" if STRICT_KERNEL_RWX && PPC_BOOK3S_32
+ depends on ADVANCED_OPTIONS
+ help
+ This option allows you to set the kernel data alignment. When
+ RAM is mapped by blocks, the alignment needs to fit the size and
+ number of possible blocks. The default should be OK for most configs.
+
+ Say N here unless you know what you are doing.
config DATA_SHIFT
- int
+ int "Data shift" if DATA_SHIFT_BOOL
default 24 if STRICT_KERNEL_RWX && PPC64
+ range 17 28 if STRICT_KERNEL_RWX && PPC_BOOK3S_32
default 22 if STRICT_KERNEL_RWX && PPC_BOOK3S_32
default PPC_PAGE_SHIFT
+ help
+ On Book3S 32 (603+), DBATs are used to map kernel text and rodata RO.
+ Smaller is the alignment, greater is the number of necessary DBATs.
config FORCE_MAX_ZONEORDER
int "Maximum zone order"
--
2.13.3
