[PATCH] ARM: zImage: ensure header in LE format for BE8 kernels
nicolas.pitre at linaro.org
Wed Jun 18 14:35:08 PDT 2014
On Wed, 18 Jun 2014, Kevin Hilman wrote:
> On Wed, Jun 18, 2014 at 11:22 AM, Stephen Boyd <sboyd at codeaurora.org> wrote:
> > On 06/18/14 11:21, Kevin Hilman wrote:
> >> On Wed, Jun 18, 2014 at 11:14 AM, Stephen Boyd <sboyd at codeaurora.org> wrote:
> >>> On 06/18/14 10:55, Kevin Hilman wrote:
> >>>> All of that to say, with this patch applied, I need a new (and
> >>>> reliable) way to determine the endianness of a kernel just by looking
> >>>> at the zImage. Recommendations welcome.
> >>> Assuming that you have the .config configured to be built into the
> >>> kernel you could use extract-ikconfig
> >>> $ ./scripts/extract-ikconfig zImage | grep CONFIG_CPU_ENDIAN_BE8
> >> Unfortunately, I can't rely on having that built in since I want the
> >> boot tools to be as generic as possible.
> > Yeah ok. Perhaps you can look for the 'setend be' instruction right
> > after the magic values instead.
> Yeah, that works, as long as I can always assume that instruction will
> be at the same offset (currently at 0x30).
Well... then you also have to test for the Thumb2 variant. And that
forces this instruction to always be there.
If we're to "officialize" this, I'd much prefer we add another magic
value like this:
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index c95feab6ce..413fd94b53 100644
@@ -128,6 +128,7 @@ start:
.word _magic_sig @ Magic numbers to help the loader
.word _magic_start @ absolute load/run zImage address
.word _magic_end @ zImage end address
+ .word 0x04030201 @ endianness flag
THUMB( .thumb )
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