xtensa: add alternative kernel memory layouts
MMUv3 is able to support low memory bigger than 128MB.
Implement 256MB and 512MB KSEG layouts:
- add Kconfig selector for KSEG layout;
- add KSEG base address, size and alignment definitions to
arch/xtensa/include/asm/kmem_layout.h;
- use new definitions in TLB initialization;
- add build time memory map consistency checks.
See Documentation/xtensa/mmu.txt for the details of new memory layouts.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 64336f6..c17496b 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -236,6 +236,50 @@
If in doubt, say Y.
+config KSEG_PADDR
+ hex "Physical address of the KSEG mapping"
+ depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX && MMU
+ default 0x00000000
+ help
+ This is the physical address where KSEG is mapped. Please refer to
+ the chosen KSEG layout help for the required address alignment.
+ Unpacked kernel image (including vectors) must be located completely
+ within KSEG.
+ Physical memory below this address is not available to linux.
+
+ If unsure, leave the default value here.
+
+choice
+ prompt "KSEG layout"
+ depends on MMU
+ default XTENSA_KSEG_MMU_V2
+
+config XTENSA_KSEG_MMU_V2
+ bool "MMUv2: 128MB cached + 128MB uncached"
+ help
+ MMUv2 compatible kernel memory map: TLB way 5 maps 128MB starting
+ at KSEG_PADDR to 0xd0000000 with cache and to 0xd8000000
+ without cache.
+ KSEG_PADDR must be aligned to 128MB.
+
+config XTENSA_KSEG_256M
+ bool "256MB cached + 256MB uncached"
+ depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
+ help
+ TLB way 6 maps 256MB starting at KSEG_PADDR to 0xb0000000
+ with cache and to 0xc0000000 without cache.
+ KSEG_PADDR must be aligned to 256MB.
+
+config XTENSA_KSEG_512M
+ bool "512MB cached + 512MB uncached"
+ depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
+ help
+ TLB way 6 maps 512MB starting at KSEG_PADDR to 0xa0000000
+ with cache and to 0xc0000000 without cache.
+ KSEG_PADDR must be aligned to 256MB.
+
+endchoice
+
config HIGHMEM
bool "High Memory Support"
depends on MMU