On 05/05/2016 02:33 PM, Aurelien Jarno wrote:
The initramfs if loaded in memory by U-Boot running in big endian mode.
When the kernel is running in little endian mode, we need to byteswap it
as it is accessed byte by byte.
Ouch!
Really it should be fixed in the bootloader, but that probably won't happen.
I wonder, is there a magic number that the initrd has? If so, we could
probe for a byteswapped initrd and not do the byte reversal unconditionally.
The logic seems correct, we need to byte swap each 8-byte aligned 8-byte
word in the image.
Cc: David Daney <david.daney@xxxxxxxxxx>
Signed-off-by: Aurelien Jarno <aurelien@xxxxxxxxxxx>
---
arch/mips/kernel/setup.c | 10 ++++++++++
1 file changed, 10 insertions(+)
Note: It might not be the best place to byteswap the initramfs not the
best way to do it. At least it shows the problem and what shoudl be done.
Suggestions to improve the patch are welcome.
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 4f60734..e7d015e 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -263,6 +263,16 @@ static void __init finalize_initrd(void)
goto disable;
}
+#if defined(CONFIG_CPU_CAVIUM_OCTEON) && defined(CONFIG_CPU_LITTLE_ENDIAN)
+ {
+ unsigned long i;
+ pr_info("Cavium Octeon kernel in little endian mode "
+ "detected, byteswapping ramdisk\n");
+ for (i = initrd_start; i < ALIGN(initrd_end, 8); i += 8)
+ *((unsigned long *)i) = swab64(*((unsigned long *)i));
+ }
+#endif
+
reserve_bootmem(__pa(initrd_start), size, BOOTMEM_DEFAULT);
initrd_below_start_ok = 1;
