Re: [PATCH 2/3] Kbuild: Implement CONFIG_UIMAGE_KERNEL_NOLOAD

[Stephen Warren <swarren@wwwdotorg.org>]

On 03/07/2012 11:08 AM, Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 17:30 Tue 06 Mar     , Stephen Warren wrote:
>> This allows the user to use U-Boot's mkimage's -T kernel_noload option
>> if their arch Kconfig allows it, and they desire.
>>
>> Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
>> ---
>> The next patch enables this new CONFIG_ALLOW_ option for ARM. I assume
>> that some other architectures will also be able to enable it, but I'm
>> not familiar enough with any to know which.
> I'm going to repeat. I don't think any impromevent here.
> 
> with no specific kernel load address the uImage for is useless/

No, the whole point of this type of kernel image is that it doesn't need
a specific load address; the kernel zImage can run from anywhere in RAM
(provided AUTO_ZRELADDR is enabled, subject to some slight
restrictions), and hence the uImage doesn't need to be loaded to or
moved to any particular location.

The scripts that U-Boot runs determine where the image gets loaded into
memory.

> And this no the job of the kernel to build a boot loader specific boot image
> format.

Not everyone agrees with this.

> And the uImage format here is called the legacy format where now U-Boot
> support a new format based on DT format.
> 
> Will you plan to add it too?

No. The last time I heard anyone talk about that, it sounded like the
adoption was basically zero, so it seems pointless. Personally, I find
creating that kind of image more complex, and don't see any benefits in
that format either.

> no sorry I don't think it's the right way to go.
> 
> On X86 we boot zImage simply. The new uImage option to do not specify the load
> address add nothing more than just boot a zImage for kernel point of view.

U-Boot does not currently have the ability to boot zImage on ARM.

> Further more on server the vendor will use grub mostly (even on ARM) and will
> expect to boot a zImage.

But that is irrelevant for the people who are using U-Boot not grub.