microblaze: Allow PAGE_SIZE configuration
Allow developer to configure memory page size at compile time.
Larger pages can improve performance on some workloads.
Based on PowerPC code.
Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index 505a085..a517421 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -223,6 +223,36 @@
hex "Size of user task space" if TASK_SIZE_BOOL
default "0x80000000"
+choice
+ prompt "Page size"
+ default MICROBLAZE_4K_PAGES
+ depends on ADVANCED_OPTIONS && !MMU
+ help
+ Select the kernel logical page size. Increasing the page size
+ will reduce software overhead at each page boundary, allow
+ hardware prefetch mechanisms to be more effective, and allow
+ larger dma transfers increasing IO efficiency and reducing
+ overhead. However the utilization of memory will increase.
+ For example, each cached file will using a multiple of the
+ page size to hold its contents and the difference between the
+ end of file and the end of page is wasted.
+
+ If unsure, choose 4K_PAGES.
+
+config MICROBLAZE_4K_PAGES
+ bool "4k page size"
+
+config MICROBLAZE_8K_PAGES
+ bool "8k page size"
+
+config MICROBLAZE_16K_PAGES
+ bool "16k page size"
+
+config MICROBLAZE_32K_PAGES
+ bool "32k page size"
+
+endchoice
+
endmenu
source "mm/Kconfig"
diff --git a/arch/microblaze/include/asm/elf.h b/arch/microblaze/include/asm/elf.h
index 7d4acf2..732caf1 100644
--- a/arch/microblaze/include/asm/elf.h
+++ b/arch/microblaze/include/asm/elf.h
@@ -77,7 +77,7 @@
#define ELF_DATA ELFDATA2MSB
#endif
-#define ELF_EXEC_PAGESIZE 4096
+#define ELF_EXEC_PAGESIZE PAGE_SIZE
#define ELF_CORE_COPY_REGS(_dest, _regs) \
diff --git a/arch/microblaze/include/asm/page.h b/arch/microblaze/include/asm/page.h
index 464ff32..c12c6df 100644
--- a/arch/microblaze/include/asm/page.h
+++ b/arch/microblaze/include/asm/page.h
@@ -23,8 +23,16 @@
#ifdef __KERNEL__
/* PAGE_SHIFT determines the page size */
-#define PAGE_SHIFT (12)
-#define PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT)
+#if defined(CONFIG_MICROBLAZE_32K_PAGES)
+#define PAGE_SHIFT 15
+#elif defined(CONFIG_MICROBLAZE_16K_PAGES)
+#define PAGE_SHIFT 14
+#elif defined(CONFIG_MICROBLAZE_8K_PAGES)
+#define PAGE_SHIFT 13
+#else
+#define PAGE_SHIFT 12
+#endif
+#define PAGE_SIZE (ASM_CONST(1) << PAGE_SHIFT)
#define PAGE_MASK (~(PAGE_SIZE-1))
#define LOAD_OFFSET ASM_CONST((CONFIG_KERNEL_START-CONFIG_KERNEL_BASE_ADDR))
diff --git a/arch/microblaze/kernel/cpu/mb.c b/arch/microblaze/kernel/cpu/mb.c
index 4216eb1..7086e35 100644
--- a/arch/microblaze/kernel/cpu/mb.c
+++ b/arch/microblaze/kernel/cpu/mb.c
@@ -126,6 +126,7 @@
cpuinfo.pvr_user1,
cpuinfo.pvr_user2);
+ count += seq_printf(m, "Page size:\t%lu\n", PAGE_SIZE);
return 0;
}
diff --git a/arch/microblaze/kernel/head.S b/arch/microblaze/kernel/head.S
index 1bf7398..4243400 100644
--- a/arch/microblaze/kernel/head.S
+++ b/arch/microblaze/kernel/head.S
@@ -43,10 +43,10 @@
.global empty_zero_page
.align 12
empty_zero_page:
- .space 4096
+ .space PAGE_SIZE
.global swapper_pg_dir
swapper_pg_dir:
- .space 4096
+ .space PAGE_SIZE
#endif /* CONFIG_MMU */
diff --git a/arch/microblaze/kernel/vmlinux.lds.S b/arch/microblaze/kernel/vmlinux.lds.S
index db72d71..b0de1a6 100644
--- a/arch/microblaze/kernel/vmlinux.lds.S
+++ b/arch/microblaze/kernel/vmlinux.lds.S
@@ -55,7 +55,7 @@
*/
.sdata2 : AT(ADDR(.sdata2) - LOAD_OFFSET) {
_ssrw = .;
- . = ALIGN(4096); /* page aligned when MMU used - origin 0x8 */
+ . = ALIGN(PAGE_SIZE); /* page aligned when MMU used */
*(.sdata2)
. = ALIGN(8);
_essrw = .;
@@ -70,7 +70,7 @@
/* Reserve some low RAM for r0 based memory references */
. = ALIGN(0x4) ;
r0_ram = . ;
- . = . + 4096; /* a page should be enough */
+ . = . + PAGE_SIZE; /* a page should be enough */
/* Under the microblaze ABI, .sdata and .sbss must be contiguous */
. = ALIGN(8);
@@ -120,7 +120,7 @@
__init_end_before_initramfs = .;
- .init.ramfs ALIGN(4096) : AT(ADDR(.init.ramfs) - LOAD_OFFSET) {
+ .init.ramfs ALIGN(PAGE_SIZE) : AT(ADDR(.init.ramfs) - LOAD_OFFSET) {
__initramfs_start = .;
*(.init.ramfs)
__initramfs_end = .;
@@ -132,11 +132,11 @@
* so that __init_end == __bss_start. This will make image.elf
* consistent with the image.bin
*/
- /* . = ALIGN(4096); */
+ /* . = ALIGN(PAGE_SIZE); */
}
__init_end = .;
- .bss ALIGN (4096) : AT(ADDR(.bss) - LOAD_OFFSET) {
+ .bss ALIGN (PAGE_SIZE) : AT(ADDR(.bss) - LOAD_OFFSET) {
/* page aligned when MMU used */
__bss_start = . ;
*(.bss*)
@@ -145,7 +145,7 @@
__bss_stop = . ;
_ebss = . ;
}
- . = ALIGN(4096);
+ . = ALIGN(PAGE_SIZE);
_end = .;
DISCARDS
