From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from majordomo by infradead.org with local (Exim 3.16 #2) id 13f3q8-0003Mm-00 for mtd-list@infradead.org; Fri, 29 Sep 2000 18:20:52 +0100 Received: from trappist.elis.rug.ac.be ([157.193.67.1] ident=root) by infradead.org with esmtp (Exim 3.16 #2) id 13f3q7-0003Mg-00 for mtd@infradead.org; Fri, 29 Sep 2000 18:20:51 +0100 Received: from rug.ac.be (polaris.elis.rug.ac.be [157.193.67.43]) by trappist.elis.rug.ac.be (8.9.3/8.9.2) with ESMTP id TAA21437 for ; Fri, 29 Sep 2000 19:20:49 +0200 Message-ID: <39D4CF6E.76E89B@rug.ac.be> Date: Fri, 29 Sep 2000 19:20:46 +0200 From: Michiel Ronsse MIME-Version: 1.0 To: mtd@infradead.org Subject: Re: SBC-MediaGX References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-mtd@infradead.org List-ID: David Given wrote: > > >after checking all the messages in the archive of this > >mailing list I managed to access the Intel Strataflash > >chip on our Arcom SBC-MediaGX board. I 'repartitioned' the flash: > >256kB for the BIOS extension, 1.5MB for DOS and the remainder > >for Linux. The linux partition was formatted with JFFS. > >Everything seems to work find although JFFS makes a lot > >of noise when mounting the partition, moreover it finds only > >13MB free and df only reports 4MB free... > > There may be sectors needing garbage collection. Try syncing it and having > another look. As for why it's so slow, I'm not sure, but someone posted a > patch a few days ago that should speed things up considerably (I haven't tried > it). It seems the JFFS image made by mk.jffs was totaly f**ked up. The garbage collector freaked out after a while (endless loop) and managed to erase the first few bytes from my FlashFX-BIOS image! However after each few reboot/ mount/garbage collections everything seems to work fine now. Actually, it works like a charm! > >The next logical step would be to make the flash bootable > >by overwriting the BIOS extension. I'm a bit reluctant to > >do this as I don't want to make my board unbootable. E.g. > >what happens if there is something wrong with the new BIOS? > >Can you prevent somehow the BIOS on the board > >from executing the BIOS extension in the flash? > > My understanding (you better check this before trying anything) is that the > BIOS extension only contains the VBF code needed for DOS to see the VBF > volume. If you trash it, all that will happen is that you won't be able to > access the VBF volume, and you can always reinstall it from the Arcom floppy. > The BIOS itself is in another flash chip entirely. I think. As I understand it, the BIOS is in the first 256kB of the flash. Disassembling the first few bytes surely look like the start of a BIOS extension (e.g. it starts with the magic numbers AA55). Actually, after the first bytes were wiped out by the garbage collector, I couldn't access the Flash-drive under DOS anymore (the FlashFX message that 'flashes' by at bootup didn't appear => no BIOS extension installed.) > > What do you have in mind for a boot loader? Good question that remains to be answered... > > >Another question: why is the BIOS extension area soo big as > >the extension itself is only about 14kB? The autoexec.bat file > >on the Arcom bootfloppy mentions that the extension was enlarged > >some time ago to 256KB in order to accomodate the Windows CE > >registry??? > > Don't know. I stuck with 256kB on my board for the same reason you did. I > don't think it's critical; what's the maximum size for a ROM extension? 16kB? > 32kB? The memory window it takes up at bootup (processor in real mode) is only 16kB big, so this seems to be the maximum. Michiel Ronsse. BTW: my board now works like a charm. The flash starts with a BIOS extension of 256kB, followed by a DOS/FlashFX partition of 1MB containing loadlin+vmnlinuz and I have a minimal Linux-system in the last partition of around 15MB. -- +- Michiel Ronsse --- michiel.ronsse@rug.ac.be -+ | Parallel Information Systems Group | | ELIS - Ghent University - Ghent, Belgium | | Phone: +32/9/264.33.67 Fax: +32/9/264.35.94 | +------ http://www.elis.rug.ac.be/~ronsse ------+ In a train station the train stops, in a work station ... To unsubscribe, send "unsubscribe mtd" to majordomo@infradead.org