Re: Kernel Header UAPI Issue

Mikko Rapeli


On Tue, Feb 23, 2021 at 06:56:02AM -0800, Karthik Poduval wrote:
Hi Mikko,

Do you have an example on how you do that ? Do you bbapend the
linux-libc-headers recipe file ?
A kernel recipe will provide linux-libc-headers after a
"make headers_install" call...

So the SRC_URI of linux-libc-headers can be the same as from the
linux kernel recipe, or linux kernel recipe can provide (with some
tricks, possibly) the linux-libc-headers binary packages.

I have an application that uses dmabuf heap that potentially extends
across multiple BSP's as its BSP agnostic. I don't want to be patching
individual BSP recipes and generating headers. The issue I am facing
is due to backporting the patch from 5.6 to 5.4 so the required header
isn't a part of the recipe. Best would have been
a virtual/kernel-keaders target that applications that require BSP
headers would add to their recipe DEPENDS. Why is this not a solved
issue by yocto project ? Why do individual BSP's need to deal with
this differently when the header install mechanism (make
headers_install) is the same irrespective of the type of BSP ?
I guess the reason is to split userspace to BSP/board specific and common
parts. It's not good if whole userspace bootstrap depends on kernel
recipe and any kernel changes requires full bootstrap and recompilation
of all userspace.

But there are BSP/board specific recipes which do need the real effective
kernel headers to interface with kernel drivers, and there are SoC
architecture specific ones which just need enough to build gcc and glibc.

Both have their pross and cons, and to me there is no clear winner.



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