Messages in this thread | | | From | John Stultz <> | Date | Thu, 8 Sep 2016 20:06:48 -0700 | Subject | Re: [PATCH] of: Overlay manager |
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On Thu, Sep 8, 2016 at 7:27 PM, Rob Herring <robh+dt@kernel.org> wrote: > On Thu, Sep 8, 2016 at 7:39 PM, John Stultz <john.stultz@linaro.org> wrote: >> On Thu, Sep 8, 2016 at 5:33 PM, Rob Herring <robh+dt@kernel.org> wrote: >>> If you can figure out how to change the command line, then you can >>> just change the dtb. At least for how Android boot works, those aren't >>> really changed separately. >> >> Ehh.. that's not so simple. The dtb is often appended to the kernel on >> Android devices. Changing the boot arguments is much simpler to do. > > How? You typically make a new bootimage assembling the kernel/dtb, > ramdisk and kernel command-line. If things were done differently such > that the dtb is part of the bootloader (how it is supposed to be > done), then I would buy the argument that we can't update the dtb and > need to either have a way to add and/or select overlays. But Android > folks like to update *everything*, so I don't buy that here.
So in many cases the dtb is appended when the kernel is built, not when the abootimg is assembled.
So its much easier to use abootimg -u to update a prebuilt boot.img in place and reflash. That way users don't need to regenerate the kernel w/ appended dtb.
thanks -john
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