RSB: Why is "/usr" the default prefix?

[Sebastian Huber]

----- Am 11. Jan 2019 um 16:30 schrieb joel joel at rtems.org:

> On Fri, Jan 11, 2019, 8:45 AM Sebastian Huber <
> sebastian.huber at embedded-brains.de wrote:
> 
>> ----- Am 11. Jan 2019 um 15:38 schrieb Sebastian Huber
>> sebastian.huber at embedded-brains.de:
>>
>> > Hello,
>> >
>> > why is "/usr" the default prefix? RTEMS does not belong to the host
>> system. I
>> > think it should be "/opt"
>> >
>> > http://refspecs.linuxbase.org/FHS_3.0/fhs/ch03s13.html#purpose14
>> >
>> > or "/usr/local"
>> >
>> > http://refspecs.linuxbase.org/FHS_3.0/fhs/ch04s09.html#purpose24
>>
>> Sorry, I mean why is it "/usr" on Linux.
>>
>> Another question, the user manual says in the prefixes section:
>>
>> "A further reason not to use the standard prefix is to allow more than one
>> version of RTEMS to exist on your host machine at a time. The autoconf and
>> automake tools required by RTEMS are not versioned and vary between the
>> various versions of RTEMS. If you use a single prefix such as the standard
>> prefix there is a chance parts from a package of different versions may
>> interact. This should not happen but it can."
>>
>> I think this is quite inconvenient from RSB to use such a prefix. Why
>> can't it use OS standard prefix (e.g. "/opt" or "/usr/local") + rtems +
>> version, e.g. "/opt/rtems/5" by default? You still have the root permission
>> problem, but the we get rid of the conflicting versions stuff.
>>
> 
> That's essentially what I always do. /opt is a very old convention I
> remember using on Solaris. Texlive installs there. Personally, I would
> recommend /opt/rtems/version or something off a home directory that is
> similar. Again, personally, I create a directory
> $HOME/rtems-XXX/tools/version where XXX indicates a project or purpose. I
> add nothing to my PATH until I commit to working in that RTEMS instance.
> This let's me keep normal work separate from new class instances away from
> customer project instances.

Yes, I think the cited paragraph sounds more like an RSB bug report to me. We should change the default OS prefix on Linux to "/opt" and use OS prefix + "/rtems/${version}" as the default prefix.