Date: Tue, 22 May 2007 09:15:34 -0700 From: Sean Bruno <sbruno@miralink.com> To: Warner Losh <imp@bsdimp.com> Cc: freebsd-embedded@FreeBSD.org Subject: Re: [nanobsd] Calculation of new flash image size Message-ID: <46531726.9050907@miralink.com> In-Reply-To: <20070522.094257.74690293.imp@bsdimp.com> References: <465233FF.8060100@miralink.com> <20070522.094257.74690293.imp@bsdimp.com>
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Warner Losh wrote:
> 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.
>
This is an IDE flash device, not a CF card or other memory stick-ish thing.
> 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.
>
After wiping the flash disk, fdisk reports the same values. The only
item of note is the "Warning" section.
mybox# 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)
fdisk: invalid fdisk partition table found
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 165 (0xa5),(FreeBSD/NetBSD/386BSD)
start 63, size 1000881 (488 Meg), flag 80 (active)
beg: cyl 0/ head 1/ sector 1;
end: cyl 992/ head 15/ sector 63
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
<UNUSED>
The data for partition 4 is:
<UNUSED>
I didn't retry as the values retrieved here are the same as I previously
had used.
Sean
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