Re: / on ramfs, possible?

["H. Peter Anvin" <hpa@transmeta.com>]

David Woodhouse wrote:
> 
> On Mon, 30 Oct 2000, H. Peter Anvin wrote:
> 
> > Pardon?!  This doesn't make any sense...
> >
> > The question was: how do switch from the initrd to using the ramfs as /?
> > Using pivot_root should do it (after the pivot, you can of course nuke
> > the initrd ramdisk.)
> 
> My question is: What do you want to do that for? You can nuke the initrd
> ramdisk, but you can't drop the rd.c code, or ll_rw_blk.c code, etc. So
> why not just keep your root filesystem in the initrd where it started off?
> 

Umm... because the size of a ramdisk is fixed, but the size of a ramfs is
flexible?

I can certainly understand this problem... I might in fact do exactly
this in the next version of my SuperRescue disk.  There, the ramdisk
which is the real root is populated from a .tar.gz file; the initrd is
just there to unpack the .tar.gz file onto the "real" ramdisk; the initrd
is then jettisoned.

Why not just have the real root be the initrd, you ask?  It's too large:
since an initrd needs to exist in both compressed form and uncompressed
form in memory at the same time; it would mean SuperRescue would no
longer work on systems with 64 MB RAM.  If I went to ramfs it might
actually work on systems with 48 MB RAM, albeit you better not need to
much space in / (or conversely, it would suddenly let you put a whole lot
more stuff in /tmp if you have 512 MB.)

	-hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
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