On Wed, Jul 19, 2017 at 12:44:48PM +1000, Bin Chen wrote: > On 18 July 2017 at 22:32, Tom Rini <tr...@konsulko.com> wrote: > > > On Thu, Jul 13, 2017 at 05:33:08PM +1000, Bin Chen wrote: > > > Hi Tom, > > > > > > Thanks for the review. > > > > > > On 13 July 2017 at 04:25, Tom Rini <tr...@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.c...@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: > > > > > > 1. 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. > > > > There's some confusion here. bootm is not only for "uImage" kernels. > > It for example handles the aarch32 Android image format. > > > > > 2. bootm path doesn't have the logic that is currently in the booti, such > > > as the > > > kernel relocation. > > > > Now I'm confused, what is different in an "Android" image for aarch64 > > than from a standard aarch64 Linux kernel 'Image' ? > > > > Android image wraps the 'Image'. There is a section called “kernel” in > Android > image, and will place the Image there [1]. Do you think it is the right way > to do that? > > I think that's the case for aarch32 android image as well, but replace the > 'Image' with > aarch32 kernel build target - I don't know what the format of that target > is. > > [1] > https://android.googlesource.com/platform/system/core/+/master/mkbootimg/bootimg.h > > > > > 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. > > > > Well, there's some discussion in the archives about this. The short > > answer is that "bootm" wasn't supposed to become a "figure out whatever > > this image is, boot it" command. > > > > Good to know the idea beyond that and what bootm isn't supposed to be. > That helps to decide whether we should stuff things into bootm or having a > separate one. > > > > In hindsight, now, I'm thinking that the aarch32 Android image support > > maybe should have gone into "bootandroid" and in turn it would be easier > > to get someone to write a new command, say "bootauto" that would ask > > bootm/bootelf/bootefi/bootandroid/bootz/booti/etc if it liked the image > > found at $address and if so, boot it, and if not, move on to checking > > the next type. > > > > That seems the idea what many people agree upon. Not sure how easy > to move aarch32 support out and I don't have a aarch32 platform to test. > Do you think we'll want to start with aarch64 (considering that may be the > aarch > for most android phone out there) and have a separate boota(ndroid) command?
I think the best path forward today is to make sure that whatever aarch64-Image support code that's needed from cmd/booti.c is available so that 'bootm' can see that we have an Android-style image and then further that we have an Image underneath it, rather than a zImage, and handle running it appropriately. I think bootm, aka "boot application image from memory" is the best place to handle both 32 and 64bit Android style images, as things stand today, at least. -- Tom
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