FC4 CF-based Router

[Steven Ringwald]

Bob Chiodini wrote:

>
>A thought about process ID's.  What is the PID of bash?
>  
>

I will have to look that up when I am in the "boot from target disk" 
part of things again; have gotten side-tracked today on other things I 
am supposed to have done, in addition to the flash. :-)

>I had similar thoughts concerning the real-root-dev trying to setup a
>bootable partition on a Disk-On-Chip a while back.  After building a
>kernel specific for the hardware, it seems that I had to run rdev to set
>up the correct root device so that I did not need a ramdisk.  It also
>seems that real-root-dev needs to be the device prior to pivot_root if
>you are using a ramdisk.  Honestly, I don't know why I think that.
>Hopefully someone will enlighten em.
>
>After thinking for a while and not trying to repeat my past mistakes,
>why not build the CF as Fedora or other distro's build a "real" disk?
>
>Build your root partition into an ext2 formated partition on your CF
>(say /dev/hda2), set up Grub in hda1 (/boot) and the MBR in /dev/hda,
>make a vfat partition in hda3 for your other OS's.  I think at this
>point you can either set the root device of your embedded kernel with
>rdev, or pass in the device with root=/dev/hda2 (e.g.).  All of the
>required device files would have to exist on your CF based root.  You
>would also need a busybox compatible /etc/inittab that runs the
>appropriate startup scripts.  Those scripts can then set up any
>additional devices, do your mounting and start whatever services you
>need.
>  
>
Ok. So you are saying, basically, to use a ext2 filesystem natively to 
boot off of and then just treat it like grub/Fedora normally treat 
partitions? Or are you saying boot the flash, and then hop over to the 
hard-drive? Problem with the latter; system has no hard-drive, and 
adding one would increase its weight/cost/number of moving parts... 
Design criteria is *very* strict on these points, and the specification 
of "no hard-drive". :-) 

If the former, the problem with that is we wanted to make it easy to 
upgrade the flash image, rather than having to include bios upgrade 
utility. Almost any system on the market right now can read/write vfat 
(Mac/Linux/Windows/BeOS)...

I have, BTW, gotten this part to work; I can boot the key in rw mode 
with this method.

>Then in theory your linuxrc can just be a link to busybox.  This should
>work whether your device is a CF or a USB stick.  Use sda instead of
>hda.
>  
>
Or label the partition and mount with LABEL=/WHATEVER, if the mount 
command within the initrd support it.

>Keep in mind that you should/must run rdev against a COPY of the kernel,
>not the one running on your desktop.
>
>You could alternately use syslinux as the boot loader instead of grub.
>hda1 would need to to be DOS-like (I used FAT12) in this case.
>  
>
Well, I guess I could do that. We thought that by making the grub 
partition ext2, and the other partition vfat, we would minimize the 
danger of accidentally overwriting the bootloader when a tech is popping 
the key into a windows box.

Steve