On 16-03-01 05:44 AM, Robert P. J. Day wrote:
Quoting Andrea Adami <andrea.ad...@gmail.com>:
On Tue, Mar 1, 2016 at 12:19 AM, Robert P. J. Day
<rpj...@crashcourse.ca> wrote:
(i posted a much lengthier version of this on oe-core recently, but
i want
to cut it down and ask specific questions to clarify what i *think*
is going
on.)
i want to pull in an existing layer with recipes for linux-4.0.bb and
linux-4.1.bb, and extend them with .bbappend files, to support two
closely-related
machines i'm defining -- call them "mach1" and "mach2". AFAICT, my
patches
will
fall somewhere in a 3x3 matrix of possibilities:
* 3 possibilities of applying against mach1, mach2 or both
* 3 possibilities of applying against linux-4.0, linux-4.1 or both
so there's my 3x3 matrix.
the obvious kernel recipe directory structure would be:
linux/
linux-4.0.bbappend
linux-4.1.bbappend
linux-4.0/ [4.0-specific patches]
linux-4.1/ [4.1-specific patches]
linux/ [patches that apply to both]
which suggests that both my .bbappend files would have to contain the
line:
FILESEXTRAPATHS_prepend := "${THISDIR}/${BP}:${THISDIR}/${BPN}"
so the SRC_URI search path for linux-4.0.bbappend entries would be
prepended with:
* linux-4.0/ [4.0-specific patches]
* linux/ [patches that apply to both]
and similarly for linux.4.1.bbappend. how am i doing so far? this would
mean that, for each recipe, the more specific directory would be
searched
before the general directory. but wait ... there's more.
now i want to further categorize patches based on exclusive to mach1,
exclusive to mach2, or applicable to both, and since the machine name is
one of the entries in FILESOVERRIDES, i can extend the directory
structure
as:
linux-4.0/
mach1/
mach2/
linux-4.1/
mach1/
mach2/
linux/
mach1/
mach2/
and there's my 3x3 matrix of patches, correct? and here's where it gets
unclear.
i really don't want to have to number all my patches with prefixes
like
0001-, 0002- and so on, so what is the ordering of processing for .scc,
.cfg and .patch/.diff files? rather than just lump all the patches into
a single .scc file, i want to refine the patches across multiple .scc
files. is there an imposed order on SRC_URI entries, .scc files and so
on? that's probably all i need to finish this off.
rday
Robert,
in the past I have done pretty much the same: scc,cfg and patches all
packed in the recipe.
Please see these (outdated) layout examples for linux-yocto* that were
in meta-handheld.
for 3.10, using .cfg & .scc
http://cgit.openembedded.org/meta-handheld/tree/recipes-kernel/linux?h=dylan
Or simplified, for 3.14, using defconfig, with patches listed in SRC_URI
http://cgit.openembedded.org/meta-handheld/tree/recipes-kernel/linux?h=dizzy
thanks, i'll check that out. first thing i want to be absolutely clear
on is, if i have multiple patch directories, i need to add them *all*
to the search path, as in:
FILESEXTRAPATHS_prepend := "${THISDIR}/${BP}:${THISDIR}/${BPN}"
and certainly in that order, as i want the more specific version
patches to be found first. so that bit is correct, yes?
next, i'm still unclear on whether there is any enforced ordering
on the processing of .scc files. i know that some folks number their
patch files as 0001-*, 0002-* and so on, in order to enforce a
patching order (because the order that one specifies patch/diff files
in the SRC_URI doesn't mean anything, correct?)
I'm waiting for someone to slap me for saying something so definitive,
but here it goes anyay ... The order in the SRC_URI definitely matters.
The order that they are specified is the order the patches are applied.
Otherwise, a patch stack of any depth wouldn't be possible. Only if you
are doing wildcard patches and rely on shell globbing would numbering
be critical.
however, i would rather not use a numbering scheme like that because,
well, it's ugly, and given that i will have patches scattered all over
the patch directories and subdirectories on a per-kernel and a
per-target board basis, it just wouldn't make much sense.
Agreed.
so my plan is to (predictably) group related patch files and .cfg
files into a number of .scc files but (again) is there any enforced
search order for .scc files? i'm assuming my setting for FILESEXTRAPATHS
and use of FILESOVERRIDES will kick in here ... will the order of
the .scc files in SRC_URI have any effect as well?
.scc files will be processed in the order they are found on the
SRC_URI, and then the patches the order they are within the .scc
files.
also, once a .scc file is located, will the location of the listed
.cfg and .patch/.diff files inside it start a whole new search process
based on FILESEXTRAPATHS and FILESOVERRIDES?
The search path is created relative to the .scc file that is referencing
a patch, and across any directory that has a .scc file in the SRC_URI.
The .scc feature descriptions are self contained, hence "reaching outside"
to a parent, or other directory structure isn't a good thing. Just list
things on the SRC_URI if that is required.
if this is all written down somewhere, just point me to it. thank
you kindly.
IIRC it is in the kernel development manual (the .scc file parts), but
the SRC_URI and patch order is common to any recipe that bitbake/oe-core
process.
rday
p.s. all of this is in aid of trying to avoid ordering mishaps when
applying patches, but i'm guessing that if i design my .scc files
carefully to be logically self-contained, i can probably avoid
accidents like that in the first place.
Correct. The .scc files, kernel-cache and management found within
the files was created to manage hundreds of patches for overlapping
boards, much like you are describing.
In the end, when complexity gets really high, a git repo with branches
is probably easier ... and with that description, I've just covered
how patch management with .scc files leads to the linux-yocto tree :)
Bruce
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