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Author: Didier Kryn
Date:  
To: dng
Subject: Re: [DNG] Giving Devuan sans-initramfs capabilities
Le 04/01/2016 18:33, Svante Signell a écrit :
> On Mon, 2016-01-04 at 17:43 +0100, Didier Kryn wrote:
>> Le 04/01/2016 17:32, Svante Signell a écrit :
>> Just an idea: Would it be possible to detect the hardware of each computer
>> being installed on and after that install the needed modules? Preferably the
>> modules should not be located on /usr, currently they are under /lib.
>>
>>       I don't understand the repulsion towards having the modules in
>> /usr/lib. What difference does it make? None, unless you want the three
>> following conditions: no initramfs, /usr being a mountpoint, some
>> drivers and filesystems compiled in the kernel, but missing just the one
>> for /usr. You've got to work pretty hard to fulfill these conditions.
> Well, the important part of my question was: "Would it be possible to detect the
> hardware of each computer being installed on and after that install the needed
> modules?"

>
> Where the modules are located is very much under discussion here and on debian-
> devel, see the "support for merged /usr in Debian" thread there. This is another
> issue that could be discussed elsewhere here.
>

     There are two places where a driver can be: either statically 
linked with the kernel, or in a loadable module. In the second case the 
kernel has some minimal interface to the driver that is to be 
dynamically loaded, and a mechanism to search and load the module from a 
file.


      There is one place for a file: within a file hierarchy. And a file 
hierarchy has the rootfs at its top, watever it is, a hard disk, a 
cdrom, a flash memory, or a ramdisk.


     If there is an initramfs, then it is the rootfs, and the kernel 
launches init. Otherwise it must first mount the rootfs, which means 
that all the drivers needed to operate the disk and the partitions and 
perform the mount must be linked statically with the kernel
  (built-in).


     It is possible to choose which drivers to have, either all 
possible, or just the ones necessary for the hardware, but they must be 
either statically linked with the kernel, or stored in files. In the 
absence of an initramfs, a minimal set of drivers must be statically 
linked with the kernel.


     Didier