Re: multibooting the linux kernel

From: Nufarul Alb
Date: Wed Aug 13 2003 - 14:41:26 EST


Jim Carter wrote:

On Wed, 13 Aug 2003, Nufarul Alb wrote:


There is a patch for the kernel that make it able to preload modules
before the acutal booting.



Perhaps I'm misunderstanding the issue, but this sounds like a job for
initrd. Someone jokingly mentioned booting wirelessly through a
cipe pipe, so you would stick iwconfig and cipe (and your RAID driver and
all the other wierd stuff) in the initrd. A lot of distros do this for you
automatically, including SuSE.

So how are the kernel and initrd images read? Grub has drivers for a fair
number of devices, and can read i86 BIOS-supported discs, conventional
Ethernet, some RAID (I think), etc. You can't load modules from your
regular filesystem until you can read your filesystem, meaning that the
module used to read your filesystem has to be provided by some other means.
Like initrd.

Hope this helps rather than smokes up the issue.

James F. Carter Voice 310 825 2897 FAX 310 206 6673
UCLA-Mathnet; 6115 MSA; 405 Hilgard Ave.; Los Angeles, CA, USA 90095-1555
Email: jimc@xxxxxxxxxxxxx http://www.math.ucla.edu/~jimc (q.v. for PGP key)



the use of initrd is a real pain in the butt. with multibooting GRUB loads the modules into memory and the kernel can take them from there. In this way the main kernel can be smaller, you won't need built-in filesystem drivers (they will be preloaded by GRUB), you will not have to recompile the entire kernel all the time, but only the modules.

The MAIN THING that a multiboot kernel will solve is the problem of module portability. I think that the reason why hardware producers are not making drivers for linux is that they have to make them open source in order to be compiled by every user. With multibooting it become possible to make a standard type of the main image of the kernel and all the modules will be built for it. So, the hardware vendors won't have to make public their sources and they will be encouraged to write drivers.

AND besides all that you can do many operations before mounting the actual root like, for example, make a module that encapsulates a nice boot animation, a progress bar, show the services start in a nice graphical way on top of the framebuffer.Of course this can be done with the current kernel, but you have to rebuild the entire kernel each time, errors will appear all the time.



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