[pacman-dev] [PATCH v3] makepkg: implement support for stripping kernel modules

[Allan McRae]

On 10/02/14 20:56, Steven Noonan wrote:
> On Sun, Feb 9, 2014 at 8:32 PM, Allan McRae <allan at archlinux.org> wrote:
>> On 10/02/14 09:26, Steven Noonan wrote:
>>> I noticed when I built a kernel package with options 'strip' and 'debug' that
>>> the debug package was missing the debug information for the kernel modules.
>>> This patch adds kernel modules to the targets for 'strip' and is compatible
>>> with the split-out debug information packages.
>>>
>>> v2: Correct logic error -- did a 'continue' after the 2nd-level case statement
>>>     instead of in the default case.
>>> v3: Oops, forgot to terminate outer case. Ran this version through the test
>>>     suite and all tests passed.
>>>
>>
>> For future reference, put comments like these ....
>>
>>> Signed-off-by: Steven Noonan <steven at uplinklabs.net>
>>> ---
>>
>> ... under this line.  That way they are ignored when committing the patch.
> 
> I'll bear that in mind, thanks for pointing it out.
> 
>>
>>>  scripts/makepkg.sh.in | 7 +++++++
>>>  1 file changed, 7 insertions(+)
>>>
>>> diff --git a/scripts/makepkg.sh.in b/scripts/makepkg.sh.in
>>> index 940e947..027fcc3 100644
>>> --- a/scripts/makepkg.sh.in
>>> +++ b/scripts/makepkg.sh.in
>>> @@ -1659,6 +1659,13 @@ tidy_install() {
>>>                                       strip_flags="$STRIP_SHARED";;
>>>                               *application/x-archive*)    # Libraries (.a)
>>>                                       strip_flags="$STRIP_STATIC";;
>>> +                             *application/x-object*)
>>> +                                     case "$binary" in
>>> +                                             *.ko)                   # Kernel module
>>> +                                                     strip_flags="$STRIP_SHARED";;
>>> +                                             *)
>>> +                                                     continue;;
>>> +                                     esac;;
>>
>> This looks fine to me.
>>
>> I notice the Arch Linux kernel package uses options=('!strip').  I am
>> lead to believe that stripping vmlinux lead to issues with building
>> modules.  Also the Arch PKGBUILD compresses the modules before it gets
>> to stripping the files.
> 
> I maintain the Arch Linux EC2 kernel, and I'm doing adventurous things
> with the packaging to make debugging a bit easier. I am looking at
> enabling CONFIG_DEBUG_INFO and adding -debug packages. That will
> indeed require removing the compression stage for the modules. In my
> experience this has had no negative impact. In fact, tools like 'perf'
> look for separate debug symbols.
> 
> As for module builds, you're correct:
> 
>   MODPOST 1 modules
> FATAL: vmlinux has no symtab?
> /usr/src/linux-3.13.2-1-ec2/scripts/Makefile.modpost:90: recipe for
> target '__modpost' failed
> make[1]: *** [__modpost] Error 1
> 
> The build still fails even if the -debug packages are installed alongside.
> 
> 
> I'd argue however that this doesn't impact this patch directly --
> splitting debug symbols from the kernel modules is OK, but stripping
> vmlinux is not. This could be worked around by:
> 
> 1. Moving vmlinux into linux-headers. vmlinux is kind of an oddball
> (only item in /usr/src/linux for the main package) -- maybe I'm
> missing context as to why it's in the 'linux' package? it seems like
> you'd need the -headers package for a module build anyway, so it can't
> be there just for module builds.
> 2. Change linux-headers to use options=('!strip'). This also avoids
> the strange side effect of having a -debug for linux *and*
> linux-headers.
> 
> I just tested the above and successfully built a module. So I guess
> the question is if vmlinux really needs to be in the primary package
> (and I'd be curious to know why, if so).
> 

That makes sense to me.  Can you create a feature request on the Arch
bug tracker to implement this.

Anyway - now that I am more clear on the situation, I think your patch
makes a lot of sense and will pull it.

Allan