Boot LFS from compact flash into ramdrive?

Mike Asher masher at bin19.com
Thu Jan 29 18:53:26 PST 2004


----- Original Message ----- 
From: "David Farrell" <dfarrell at protoparts.com>
Newsgroups: lfs.support
To: <lfs-support at linuxfromscratch.org>
Sent: Thursday, January 29, 2004 8:08 PM
Subject: Re: Boot LFS from compact flash into ramdrive?


> Ken Moffat wrote:
> > On Mon, 26 Jan 2004, BoB wrote:
> >
> >
> >>I'd like to boot from the CF card in a read-only fashion, loading an LFS
> >>system to a ramdrive.  Are there any docs that describe this more in
depth?
> >>Can someone offer a pointer or some assistance?  FWIW, I already have a
dev
> >>box running SuSE, so I'll only be running LFS on the other device.
> >>
> >
> >
> >  Not quite what you asked, but there's the readonly_rootfs.txt hint at
> > your local mirror (i.e. '/' is read only, so much less needs to be in
> > your ramdrive, but access to the CF is reputed to be slow).
> >
> > Ken
>
> I am running a EPIA ME-6000 with a Sandisk UltraII series compact flash.
> These CF cards are not slow, quite the contrary.  The only thing I tried
>   to eliminate was a swap partition.  I figured heavy activity was bad
> for the card.  When I tested with a swap partition, there was very
> little virutal memory activity, so this assumption was probably not a
> good one.  I do leave the root ext2 R/O and have a separate ext3
> partition for /var and /tmp.  I build the image with the uname hack for
> a i486 processor.  I use the same card with a Tsystems TS-5500 which
> uses the AMD elan processor.  I have a number of these boards "in the
> field" for the past several years running LFS with Interbase SQL.
>

If you want a bit of extra performance, you can get around the i486
limitation on the Epias.  The problem is a bug in GCC (they lack one of the
optional cmpxchg cmovs, but gcc assumes they have it).  With the newest
gccs, you can specify C3, with older ones you can just hack the opcode out
of gcc's md rules table.

BTW, the Nehemiah+ cores are supposed to implement this; I've not verified
it myself.

-
Mike




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