Date: Tue, 22 May 2007 09:42:57 -0600 (MDT) From: Warner Losh <imp@bsdimp.com> To: sbruno@miralink.com Cc: freebsd-embedded@FreeBSD.org Subject: Re: [nanobsd] Calculation of new flash image size Message-ID: <20070522.094257.74690293.imp@bsdimp.com> In-Reply-To: <465233FF.8060100@miralink.com> References: <465233FF.8060100@miralink.com>
next in thread | previous in thread | raw e-mail | index | archive | help
From: Sean Bruno <sbruno@miralink.com>
Subject: [nanobsd] Calculation of new flash image size
Date: Mon, 21 May 2007 17:06:23 -0700
> If the manufacturer doesn't provide me with the specific values for
> NANO_SECTS, NANO_HEADS and NANO_MEDIASIZE, I assume that I would be able
> to use the output of fdisk to calculate it for me:
>
> fmybox# fdisk /dev/ad0
> ******* Working on device /dev/ad0 *******
> parameters extracted from in-core disklabel are:
> cylinders=993 heads=16 sectors/track=63 (1008 blks/cyl)
>
> parameters to be used for BIOS calculations are:
> cylinders=993 heads=16 sectors/track=63 (1008 blks/cyl)
>
>
> So in this case, NANO_SECTS=63, NANO_HEADS=16 and NANO_MEDIASIZE=(993 *
> 16 * 63)=1000944?
>
> I added the following to Flashdevices.sub:
>
> dom512m)
> # Source: sbruno@miralink.com
> NANO_MEDIASIZE=`expr 512483328 / 512`
> NANO_HEADS=16
> NANO_SECTS=63
> ;;
The flashdevices.sub database is lame. It is a misfeature to require
it.
> If I do this for my new Transcend module, the system won't boot properly
> and freezes on the BTX boot loader startup.
>
> What am I doing wrong here?
There's a fundamental flaw in nanobsd. That is that it requires one
to know the geometry of the target device. fdisk won't tell you this
when you are using a scsi card reader, so you can't find it out
automatically. This is because the scsi layer uses a fake geometry
here (I can't recall if it is FreeBSD software, or the card reader).
Nanobsd is supposed to use 'packet mode' so that geometry doesn't
matter. You should make sure that the CF/disk created is in packet
mode.
If you have a card that you've re-fdisked since you bought it, dd
about 30k of zeros to the front of it from /dev/zero. Then insert it
into a camera that can do the formatting of flash cards. Put that
back into your freebsd box and run fdisk again and see what the
partitions look like.
You'll see something that looks like:
fdisk da0
******* Working on device /dev/da0 *******
parameters extracted from in-core disklabel are:
cylinders=CCC heads=HHH sectors/track=SSS (SSS * HHH blks/cyl)
Figures below won't work with BIOS for partitions not in cyl 1
parameters to be used for BIOS calculations are:
cylinders=CCC heads=HHH sectors/track=SSS (SSS * HHH blks/cyl)
Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 6 (0x6),(Primary 'big' DOS (>= 32MB)
start SSS, size XXX (YYY Meg), flag 80 (active)
beg: cyl 0/ head 1/ sector 1;
end: cyl CCC/ head HHH/ sector SSS
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
<UNUSED>
The data for partition 4 is:
<UNUSED>
CCC, HHH and SSS are the numbers you need.
Also, you can put this card in your target device and look at the BIOS
in that target device. It will tell you what it thinks it is.
Warner
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20070522.094257.74690293.imp>