:: Re: [DNG] /usr to merge or not to m…
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著者: Didier Kryn
日付:  
To: dng
題目: Re: [DNG] /usr to merge or not to merge... that is the question??
Le 16/11/2018 à 10:50, Rowland Penny a écrit :
> On Fri, 16 Nov 2018 22:11:17 +1300
> Daniel Reurich<daniel@???> wrote:
>
>> Hi Devuan followers, fans and friends,
>>
>> Debian as of the upcoming Buster release looks to be implementing a
>> merged /usr by default. At this stage there is no plan to make it
>> forced... but you never know what happens when their Technical
>> Committee suddenly decides it's an issue they need to force a
>> decision on...
>>
>> So... for Devuan, do we want to default to a merged /usr in our coming
>> release of Beowulf or are we going to resist another pointless
>> rearranging of the deck chairs...
>>
>> Keen to get some feedback on this
>>
>> Cheers,
>>     Daniel
> Can anybody explain the bad points of doing the merger ?
> I ask this because everything I can find says it is a good thing, but
> they said systemd was a good thing ;-)


    The advantage of separating /usr is it can be mounted after boot.
/bin and /sbin (and /lib) contain the critical applications (and
library) necessary to boot the system, and they are, by necessity, part
of the root filesystem. Merging /usr means, actually merging /usr/bin
with /bin, /usr/sbin with /sbin and /usr/lib with /lib.

    Merging /usr means all the bloat from /usr/bin and /usr/lib will
now be in /bin and /lib (not so much bloat in /usr/sbin). This has very
little to do with the use of an initramfs. Only in corner cases would it
prevent booting without an initramfs. Initramfs has been in use for at
least 15 years in Debian and you cannot escape it if you use the stock
Debian/Devuan kernel. You can write your own initramfs along with
compiling your own kernel if you fancy something special, it's
relatively easy and sometimes necessary, but you must take care that the
Devuan init system finds the OS in the same state it finds it after the
stock initramfs.

    If you want to boot directly to the disk, then don't use a distro.
This isn't anything new. Initramfs is the easy way for distros to
provide all possible device drivers as module. Otherwise, your kernel
should be compiled according to the hardware detected by the installer.

    The kernel is able to do such things as booting to a root
filesystem on a RAID or to a root filesystem mounted through NFS. These
techniques have been implemented long before the advent of initramfs,
but a custom initramfs can allow you to do it with more flexibility.

    The only serious issue with the "merge" is "do we want all that
bloat in /bin and /lib?" Personnally I would prefer to break it down
into /usr/editors, /usr/internet, /usr/office, /usr/games etc...

        Didier