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Date:      Fri, 11 Sep 1998 08:10:02 +0200 (CEST)
From:      Andrzej Bialecki <abial@nask.pl>
To:        eric <eric@tarsier.domain.net>
Cc:        Dennis <dennis@etinc.com>, hackers@FreeBSD.ORG
Subject:   Re: Boot from Flash
Message-ID:  <Pine.BSF.4.02A.9809110801430.2368-100000@korin.warman.org.pl>
In-Reply-To: <19980910193501.55698@tarsier.domain.net>

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On Thu, 10 Sep 1998, eric wrote:

> On Thu, Sep 10, 1998 at 04:30:36PM -0400, Dennis wrote:
> > 
> > Has anyone used the PC plug-in PCMCIA flash cards successfully with
> > FreeBSD?  If so can you boot from it without a HD?

> I've done some work with this. Yes, you can boot off the flash card just as if
> it were a disk. However, there are some problems. Due to the nature of the
[...]

Excellent explanation, Eric. I came to the same conclusions when doing
tests with an IDE flash disk. We may also add here, specifically, that
swapping on such device is something which should never be done - so this
means you probably have to live without swap, and you have to carefully
watch over your memory consumption, otherwise your processes will be
killed.

Dennis, you may want to subscribe to freebsd-small, which discusses these
issues. It's a low volume and (thus far, thank God) strictly technical
list...

> elsewhere. An ideal solution would be to have a ramdisk union-mounted
> on top of the read-only flash, and then as part of the shutdown procedure
> write the contents of the ramdisk over the flash once. Unfortunately you
> can't do this in freebsd because the union filesystem isn't usable.
> (you can mount it, but the kernel panics if you try to access anything in it)

Not that I tested it thoroughly... but last time I used mount_union in
3.0-current (a week ago?) it worked ok. YMMV as usual :-)

Andrzej Bialecki

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