[PATCH] i386: Implement CONFIG_PHYSICAL_ALIGN
o Now CONFIG_PHYSICAL_START is being replaced with CONFIG_PHYSICAL_ALIGN.
Hardcoding the kernel physical start value creates a problem in relocatable
kernel context due to boot loader limitations. For ex, if somebody
compiles a relocatable kernel to be run from address 4MB, but this kernel
will run from location 1MB as grub loads the kernel at physical address
1MB. Kernel thinks that I am a relocatable kernel and I should run from
the address I have been loaded at. So somebody wanting to run kernel
from 4MB alignment location (for improved performance regions) can't do
that.
o Hence, Eric proposed that probably CONFIG_PHYSICAL_ALIGN will make
more sense in relocatable kernel context. At run time kernel will move
itself to a physical addr location which meets user specified alignment
restrictions.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
diff --git a/include/asm-i386/boot.h b/include/asm-i386/boot.h
index 96b228e..8ce79a6 100644
--- a/include/asm-i386/boot.h
+++ b/include/asm-i386/boot.h
@@ -12,4 +12,8 @@
#define EXTENDED_VGA 0xfffe /* 80x50 mode */
#define ASK_VGA 0xfffd /* ask for it at bootup */
-#endif
+/* Physical address where kenrel should be loaded. */
+#define LOAD_PHYSICAL_ADDR ((0x100000 + CONFIG_PHYSICAL_ALIGN - 1) \
+ & ~(CONFIG_PHYSICAL_ALIGN - 1))
+
+#endif /* _LINUX_BOOT_H */