Re: [PATCH 08/36] AArch64: Kernel booting and initialisation

From: Catalin Marinas
Date: Mon Jul 23 2012 - 13:58:56 EST


On Mon, Jul 23, 2012 at 06:48:12PM +0100, Stephen Warren wrote:
> On 07/08/2012 03:18 AM, Catalin Marinas wrote:
> > On Fri, Jul 06, 2012 at 10:32:54PM +0100, Stephen Warren wrote:
> >> On 07/06/2012 03:05 PM, Catalin Marinas wrote:
> >>> The patch adds the kernel booting and the initial setup code.
> >>> Documentation/aarch64/booting.txt describes the booting protocol on the
> >>> AArch64 Linux kernel. This is subject to change following the work on
> >>> boot standardisation, ACPI.
> ...
> >>> +4. Call the kernel image
> >>> +------------------------
> >>> +
> >>> +Requirement: MANDATORY
> >>> +
> >>> +The decompressed kernel image contains a 32-byte header as follows:
> >>> +
> >>> + u32 magic = 0x14000008; /* branch to stext, little-endian */
> >>> + u32 res0 = 0; /* reserved */
> >>> + u64 text_offset; /* Image load offset */
> >>> + u64 res1 = 0; /* reserved */
> >>> + u64 res2 = 0; /* reserved */
> >>> +
> >>> +The image must be placed at the specified offset (currently 0x80000)
> >>> +from the start of the system RAM (aligned to 2MB) and called there.
> >>
> >> Is "0x80000" meant to have an extra "0"; 0x80000 isn't aligned to 2MB
> >> unless I'm really missing too much sleep today.
> >
> > The value is correct, it wasn't meant to be aligned to 2MB. Why would
> > that be? It's just an offset from the start of the RAM, which must
> > indeed be 2MB aligned (PHYS_OFFSET).
>
> Oh, I see, it's the start of SDRAM that's aligned to 2MB, not the offset
> from the start of SDRAM that needs to be aligned to 2MB. The wording
> seems slightly unclear to me. Perhaps just drop the mention of alignment
> at all, or add "which is" before "aligned to 2MB"?

I'll probably just another sentence to make it clear that it refers to
the start of the RAM.

Thanks.

--
Catalin
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