Date: Fri, 6 Aug 1999 07:24:18 -0700 (PDT) From: papowell@astart.com To: freebsd-small@FreeBSD.ORG, jay@oneway.com Subject: Re: HowTo: Making bootable FlashRom Images. Message-ID: <199908061424.HAA01942@h4.private>
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> From owner-freebsd-small@FreeBSD.ORG Fri Jul 30 15:05:49 1999
> Date: Fri, 30 Jul 1999 18:03:30 -0400 (EDT)
> From: Jay Kuri <jay@oneway.com>
> To: freebsd-small@FreeBSD.ORG
> Subject: HowTo: Making bootable FlashRom Images.
>
>
> Late but not forgotten... Skip to the very bottom for the ultra-short
> version.
>
> These are the instructions for making bootable FlashRom images using
> PicoBSD 0.44. The devices I use are have an IDE-controller chip which
> makes them look to the system like IDE drives. But there is no reason
> that these instructions can't be applied to another type of flash rom
> with only minor modifications.
>
> The process is suprisingly easy.
>
> First you need to know the layout of your device. IE: it's disklabel.
> The roms I use masquerade as IDE drives, so I just created a standard
> disklabel using the geometry of the drive as taken from the bios.
> The easiest way to do this if you have the device hooked up to a running
> FreeBSD system, is to go into sysinstall and set it up in the
> partition/label section.
>
> Basically what you have to do is create an entry in the /etc/disktab file.
> For our 8M flash, this is the disktab entry we used:
>
> flash8:\
> :dt=ESDI:ty=winchester:se#512:nt#4:ns#16:nc#250:\
> :pa#16000:oa#0:ta=4.2BSD:ba#8192:fa#1024:\
> :pc#16000:oc#0:
>
> The first line is the key (name) of the disktab entry, the second line
> sets the geometry of the drive, 4 heads, 16 sectors/track and 250
> cylinders (nt#4, ns#16, and nc#250). The third line sets the 'a' slice,
> occupying the whole disk (pa#16000 or 16000 sectors, oa#0 (offset 0)), and
> containing a ffs (4.2BSD) filesystem. Then the 'c' slice is defined, again
> with the pc#16000 and oc#0 values. (see the top of the disktab file for
> a better explanation of disktab entries)
>
> Now comes the modifications. Remember that this is based on the 0.44
> PicoBSD distribution, not the new Makefile-based one. I don't know how
> different it is...
1. You do what you have done above. I like the layout - very nice.
2. In the CONFIG file you put:
#SIZE= 2400
#FLOPPY_SIZE= 1440
#FLOPPY_FS= fd1440
# size of the MFS file system - You can put more files on this
# or you can increase the space. Note: each 1 Meg increase takes
# about 1K of image space. You lose a corresponding amount of memory
# for processes. Lets make it 4.8 Megabytes
SIZE= 4800
# You have 4 * 16 * 250 / 2 = 8000 K bytes of flash, so you can use them
FLOPPY_SIZE= 8000
FLOPPY_FS= flash8
>
> In the stage3 file, find the line that contains the dd to picobsd.bin
> command (about line 20). The count parameter will be set to 1440. This
> is the size in K. For my rom, I use 8000 (since that is the actual size
> of our rom). This value will be half the pc# value we entered above.
>
> Then we go down to the disklabel line (~ line 36). Find the fd1440 and
> replace it with the key you entered in the disktab file. For this
> example, 'flash8' is the correct value.
>
> Depending on the size of your MFS filesystem, you may want to increase the
> INODES in stage1.
>
> That covers the changes you need to make in the scripts.
>
> There are some other changes that need to be made in order for your new
> PicoBSD-Flash to work. Your best bet is to create a custom picobsd type
> (just copy the one that most closely matches the features you want). I
> used net.
>
> The first thing you have to do is make sure that your PicoBSD kernel
> supports whatever type of device your flash drive is detected as. Since
> ours is an IDE device, we need to enable the ide devices (wdc0, wd0, wd1,
> etc). You do this by editing the PICOBSD config file in the conf/
> directory.
>
> You also have to add the devices to your MFS filesystem. You do this by
> editing the Makefile in the mfs.tree directory. On approximately line
> 37, add the devices for your IDE drive (wd0h is a good way to get all of
> the slices you need), along with any other devices you want (I added ttyd0
> for my console port).
Done already...
>
> Now that you have support for your IDE device configured into your PicoBSD
> kernel, and the devices set up, you have to change the way the system
> boots.
>
> Normally after PicoBSD boots, it mounts the floppy drive and copys files
> off of it onto the MFS filesystem it created. Obviously, we need to make
> it mount the flash instead. There are two files you need to change to do
> this. These files are in the lang directory. Edit the mfs.rc.(language)
> file (in my case mfs.rc.en) and find the line that mounts the floppy ( ~
> line 24) and change the fd0 device to your flash device. I used wd0c.
> Now edit the update.(language) script and do the same thing, make sure you
> get the umount command as well).
>
> WARNING: If you enter the wrong device or do not create the
> device nodes, your flash will NOT work, it will enter a horrible infinite
> loop running /etc/rc again and again until you reboot.
Ummm... there is a simple change that will fix this behaviour.
Change the line in lang/mfs.tree/etc/rc.{en,pl} which reads:
. rc
to :
. rc.local
Rename lang/floppy.tree/etc/rc.{en,pl} to lang/floppy.tree/etc/rc.local.{en,pl}.
Now if it does not find rc.local it will continue on and exit.
>
> Thats it.
>
> When you run the build script, and select your custom configuration, it
> will create a picobsd.bin file that is the correct size for your flash
> device. You should be able to dd the file directly onto your flash and
> then boot from it.
>
>
> Oh.. and one last thing. Be VERY careful when dumping the image to your
> flash (esp. if it is an IDE-type) because it is very easy to mistype and
> overwrite your REAL drive with your picobsd distribution. Let me tell
> you, until I did that, I'd never seen a FreeBSD machine die so hideously.
> =)
>
> Good luck, and please send me feedback and/or better ways to do these
> things.
>
> Take it easy,
> Jay
>
> PS: Short version:
>
> 1: create a disktab entry for your flash device
>
> 2: edit stage3 so that it creates the right size picobsd.bin image and
> uses the disktab entry you created (instead of fd1440) to disklabel the
> file.
>
> 2a: If you are going to have a larger MFS filesystem, edit INODES in
> stage1.
>
> 3: Add your flashrom device to the PICOBSD kernel config file (wd0 in our
> case)
>
> 4: Add your flashrom device to the Makefile in mfs.tree
>
> 5: Edit lang/mfs.rc.(lang) so that it mounts the flash device instead of
> the floppy device.
> 5a: Edit lang/update.(lang) to do the same.
>
> 6: build it, dd it and watch it work. =)
>
>
>
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