On 11-09-03 7:32 AM, Chris Tapp wrote:
On 2 Sep 2011, at 16:49, McClintock Matthew-B29882 wrote:
On Fri, Sep 2, 2011 at 2:26 AM, Chris Tapp <opensou...@keylevel.com>
wrote:
However, kernel configuration becomes a little bit more complicated
as this
is done by machine name. A kernel recipe will be needed for each machine
(e.g. for the different sound drivers), but I can't work out how to
do this
using a base configuration for the SoCs that are shared and then adding
machine specific parts. I can do it using (for example) a .defconfig for
each machine, but that would require updates to multiple files to
change the
SoC configuration.
I guess what I'm really asking is, is it possible to have a base CPU
configuration and add a machine configuration to this ?
I've recently seen discussion of .cfg kernel fragment files. Are
these what
I should be looking at? Are these available in the releases or only
in the
development branch?
I think this is a good solution for you. It's a little confusing to
find were this work is but you can look in the linux-yocto kernel tree
- then the actual cfg fragment stuff on different branches.
http://git.yoctoproject.org/cgit/cgit.cgi/linux-yocto-3.0/
meta branch contains meta/ which contains a lot of the cfg fragments,
and patches, etc.
Thanks, I can see what they look like now ;-)
What are 'the rules' for cfg files? I.e.:
1) Does adding #CONFIG_this_bit not set
disable a node and its dependencies? For example, if I turn off usb
serial support do the usb serial drivers get disabled as well or do I
have to do this manually?
There's no extra processing on top of what LKC gets you, so yes,
that's how it would work. If you disable a top level option in
your fragment, lkc will then disable everything that depends on it.
2) Similarly, if a node is enabled what happens to the dependent nodes?
Do they all need to be covered, or only the ones that need to be enabled?
Same as #1. If you select FOO, you can now select anything that
depends on FOO. If FOO has its own "select BAR" statements in it,
they'll be enabled in the final .config.
So just cover what needs to be enabled.
I've also noticed that there are scc files. These seem to pull features
in to sets? How do these work?
It's best to check the yocto kernel manual for some desriptions on
this, rather than me writing it all here. I also have an updated set
of docs for 1.1 that I can send along shortly.
The .scc files are feature descriptions that cover patches (if you
have any), git operations (if you have any) and configuration. They
allow a feature and configuration to be kept together and associated.
Once in a .scc file, that feature + config can be re-use and imported
by other features.
meta/cfg/kernel-cache/bsp/common-pc/hardware.cfg contains
CONFIG_ATH5K
CONFIG_ATH_COMMON
...
CONFIG_SERIAL_8250_CONSOLE
It seems as if this file does something else, as these don't look like
valid kernel configuration options.
Covered in some of the docs, but there is a kernel configuation audit that
runs at the end. It is intended to let the user know if something they
didn't expect happened. i.e.:
- you had CONFIG_FOO=y in your fragment, but the final .config didn't
or had it as another value.
- high level configuration fragments are supposed to set non-hardware
options that are a 'policy' for the system. And BSPs should be setting
hardware options. These are the "kconf hardware <foo>.cfg" and
"kconf non-hardware <bar>.cfg" that you see in the files. If a BSP
option overrides a system policy (and hence may behave differently
in an important way), you get a warning.
- if an option is repeated you get a warning
- if a BSP sets a non-hardware option you get a warning. The config
audit has 'buckets' for options that are hardware and non-hardware,
so it can emit this warning. But that's not perfect. If a BSP developer
says 'hey, this IS hardware for my board', you can list those options
in "hardware.cfg" in your BSP dir and the audit system will leave
these options out of testing.
There is also a document in the git repo as well which is worth a look.
I couldn't see one, but there's a lot in there ;-)
Sorry for all the questions, but there's a lot to understand for someone
new :-)
Check the docs of the yocto twiki page for some theory and examples. And
I'm happy to fill in any blanks (since those would be doc gaps, and I'll
write something up).
Bruce
Chris Tapp
opensou...@keylevel.com
www.keylevel.com
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