On Thu, Jul 13, 2017 at 2:33 AM, Bin Chen bin.chen@linaro.org wrote:
Hi Tom,
Thanks for the review.
On 13 July 2017 at 04:25, Tom Rini trini@konsulko.com wrote:
On Tue, Jul 11, 2017 at 03:56:04PM +1000, Bin Chen wrote:
It's my understanding that we are supposed to use booti, instead of bootm, for arm64 image. But booti lacks of android image support. Bootm has the andriod image support but lack of the arm64 image handling.
So, what is suppose the right way of booting an android arm64 image? or, should we create a separate command?
This patch is an invitation for that discussion.
It *hacked* the booti command and it aslo assume the dtb is in the second area of android boot image. It also has other belives like u-boot should be in control of where to put the kernnel/ramdisk/dtb images so it ignores the value specified in the android images.
Signed-off-by: Bin Chen bin.chen@linaro.org
So, booti is very much for the "Image" format described in the Linux kernel in Documentation/arm64/booting.txt. One can (and people have) used bootm on aarch64 for "uImage" style kernels and FIT kernels, and I would see being able to boot an aarch64 Android image with bootm as the way to go forward.
Are you suggesting that we should use bootm path, instead of booti?
I have two questions regarding this:
- currently arm64 kernel don't have a uImage kernel target. And I'm not
sure if adding that will be something that is wanted and/or sensible.
Sure it does. You just run mkimage with the Image and create one. I suppose you mean that step is not integrated into the kernel build. That is not wanted. As Daniel pointed out, a uImage is platform specific is the first reason. Also, putting every bootloader's custom format into the kernel build doesn't really scale.
- bootm path doesn't have the logic that is currently in the booti, such as
the kernel relocation.
Also, one other question raised during internal discussion was why the booti was created in the first place, if we could have had that implemented in the bootm path.
I think for simplicity. The bootm logic and command line options are already complicated enough. Of course with that logic, we should have made Android images a separate command too (some pre-mainline versions of Android boot support did do a boota command). Though, IIRC I think you can boot an Android boot image containing a uImage for the kernel (not something I'd recommend).
Rob