[PROPOSAL] ARM/FDT: passing multiple binaries to a kernel
Andre Przywara
andre.przywara at linaro.org
Fri Sep 6 09:30:47 EDT 2013
On 09/05/2013 03:23 PM, Rob Herring wrote:
> On Wed, Sep 4, 2013 at 3:43 AM, Andre Przywara
> <andre.przywara at linaro.org> wrote:
>> On 09/04/2013 12:00 AM, Rob Herring wrote:
>>>
>>> On Tue, Sep 3, 2013 at 10:53 AM, Andre Przywara
>
>>> But surely there would be some advantage of reuse by using the
>>> multi-boot protocol since Xen, grub, and OS tools already support it
>>> for x86.
>>
>>
>> Yes, but that is x86 only and multiboot is it's nature quite architecture
>> specific. The current(?) multiboot v2 spec has no official ARM support (only
>> x86 and MIPS), so this would need to be "invented" first. While this is
>> technically easy, ARM software currently has no support for multiboot at
>> all: not in u-boot and not in Xen.
>> Multiboot support in Xen lives entirely in the x86 directory, and big parts
>> of it are even in assembly.
>
> If so, I cannot find the assembly and most of it seems to be moved out
> of x86 code now.
There is some code that relocates and maps the multiboot structure: in
files in the xen/arch/x86/boot directory, including head.S, reloc.c and
setup.c.
That would need to be completely rewritten, not only because it deals
with multiboot v1, but also because it is scattered throughout the x86
setup code and the initial page setup is different from ARM.
All these things are also done on ARM - but for the device tree already.
Of course proper multiboot v2 support is doable - but please compare the
effort needed for this against this one:
http://lists.xen.org/archives/html/xen-devel/2013-09/msg00359.html
Regards,
Andre.
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