[OE-core] Why is systemd installed to / (was: [yocto] Export bitbake variables between recipes)

[ChenQi]

On 12/04/2014 09:34 PM, Peter Kjellerstedt wrote:
>> -----Original Message-----
>> From: openembedded-core-bounces at lists.openembedded.org
>> [mailto:openembedded-core-bounces at lists.openembedded.org] On Behalf Of
>> Mark Hatle
>> Sent: den 3 december 2014 16:47
>> To: Peter Kjellerstedt; openembedded-core at lists.openembedded.org
>> Subject: Re: [OE-core] Why is systemd installed to / (was: [yocto]
>> Export bitbake variables between recipes)
>>
>> On 12/3/14, 9:36 AM, Peter Kjellerstedt wrote:
>>>>> Can anyone please explain why OE-core installs systemd to /
>>>>> rather than /usr? Because I have traced the recipe all the
>>>>> way back to its introduction in OE classic, and I cannot
>>>>> find any rationale for this odd decision. And it is extra
>>>>> weird given the systemd authors' agenda that everything
>>>>> should be in /usr (and /etc)...
>>>> It's only strange compared to Fedora.  We're not Fedora.. and
>>>> I've got systems that need to boot from a small '/' before
>>>> mounting '/usr'.
>>> Speaking of Fedora, would an official image feature, e.g.,
>>> "unified-fs", be acceptable for OE-Core that sets up the file
>>> system with /bin, /sbin and /lib* as links to their /usr
>>> counterparts? That would alleviate our problems with the
>>> differences in how systemd is installed.
>> The system permits developers to set the paths for the various pieces.
>> To get a Fedora like unified filesystem, you could do something like:
>>
>> * provide your own fs-perms.txt:
> I had not noticed fs-perms.txt before. And it seems easy enough
> to extend via the FILESYSTEMS_PERMS_TABLES variable. :)
>
>> /usr/bin	link	${base_bindir}
>> /usr/sbin	link	${base_sbindir}
>> /usr/lib	link	${base_libdir}
>>
>> Then in your local.conf:
>>
>> bindir = "${base_bindir}"
>> sbindir = "${base_sbindir}"
>> libdir = "${base_libdir}"
> I think you mean the opposite, i.e., that /bin should be a
> link to ${bindir} and ${base_bindir} should be set to ${bindir},
> but I get your point.
>
>> This will result in /usr/bin, sbin and lib being linked to /bin,
>> /sbin, /lib -- and all of the package produced for your
>> configuration will only reference '/'.
>>
>> This isn't that unusual of a configuration from what I've been told.
> Which is why I think it warrants an official distro feature (an
> image feature, as I originally suggested, will of course not do
> if it is done the way you suggest since the packages' contents
> are modified). That way people would not have to invent the wheel
> over and over again (and somehow find out that there is such a
> thing as fs-perms.txt which up until now had eluded me).
>
>> --Mark
> //Peter
>

Hi Peter,

It's easy to link /usr/bin to /bin, /usr/sbin to /sbin and make things 
work in OE.
But if we want the opposite to work, we might need several additional 
patches to OE.

Several days ago, I tried to do /usr merge in OE (like what Fedora and 
Arch does). It turned out that we need to patch several packages to make 
things work.

(I haven't sent out the patches because it's just some initial 
investigation and I'm not sure if people want this feature or not.)

If you want this feature in OE, please open a bug/enhancement in 
bugzilla https://bugzilla.yoctoproject.org/ to see if the community 
wants it or not.

Regards,
Chen Qi