[yocto] auto kernel version

[Paul Barker]

On Sat, 18 Mar 2017 04:07:05 -0400
Trevor Woerner <twoerner at gmail.com> wrote:

> Hi,
> 
> Let's say I wanted to create a recipe to follow Linus' mainline or a
> recipe to follow GregKH's staging-next. In those cases I wouldn't
> want to nail them down with a version, I'd want to do AUTOREV. So I
> wouldn't put a version in the recipe filename (linus-mainline.bb or
> gregkh-staging-next_git.bb). But I can't seem to get away with not
> having some sort of version string (LINUX_VERSION, PV) in the recipe
> itself. Is it not possible to extract a PV or LINUX_VERSION
> automatically? Otherwise I'll need to update the recipe and commit
> with every release (which isn't the end of the world, but adds to the
> maintenance).
> 
> 	SUMMARY = "GregKH's Staging-Next"
> 	SECTION = "kernel"
> 	LICENSE = "GPLv2"
> 
> 	inherit kernel
> 	require recipes-kernel/linux/linux-dtb.inc
> 
> 	LIC_FILES_CHKSUM =
> "file://COPYING;md5=d7810fab7487fb0aad327b76f1be7cd7"
> 
> 	SRC_URI =
> "git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git;branch=staging-next"
> SRC_URI_append_rk3288 = " file://defconfig"
> SRC_URI_append_intel-corei7-64 = " file://defconfig" SRCREV =
> "${AUTOREV}"
> 
> 	LINUX_VERSION = "4.11"
> 	PV = "${LINUX_VERSION}+git${SRCPV}"
> 	S = "${WORKDIR}/git"
> 
> 	DEPENDS += "xz-native bc-native coreutils-native"

The problem here is that bitbake needs to know the PV value before
starting do_fetch, as PV becomes part of the path to the work directory
for this recipe. There is special handling in the git fetcher to
resolve AUTOREV during parsing, but it just uses 'git ls-remote' (if I
remember correctly) instead of doing a full git fetch. So at the minute
it's not possible to use 'make kernelversion' or something similar to
determine PV.

For my staging recipes I've just settled for LINUX_VERSION being 4.9
for everything in the 4.9 series, from 4.9-rc1 to the latest 4.9.14.
That way you only need to modify the recipe when you jump from one
mainline release to the next. It's not ideal, but it works for me.

Thanks,
Paul