Subject: Re: Embedded Linux
From: Christopher E. Brown (cbrown@spruce.woods.net)
Date: Fri Mar 22 2002 - 15:13:09 AKST
On 22 Mar 2002, Jon Reynolds wrote:
> I would like to build a VPN, router and firewall in one small box with
> no moving parts. Essentially, I want to build a box the size of a cable
> modem box. I have read a little about DiskOnChip but not sure if this is
> what I want. Does anyone have a link to something like this?
>
> Jon
DiskOnChip (A specific brand and type) is supported in later kernels.
I have done systems using DoC units, and would have to say don't.
Depending on the version and exact type it can be hell to get a proper
multistage boot going (cannot normally use a DoC as a root device, even
read only, only usable for a multistage boot to a ramdisk).
Take a look at SanDisk (company name). One of there product lines is
industrial FLASH drives in IDE spec. You can get 2.5 or 3.5 inch
format bootable IDE devices from 4MB to 512MB and beyond.
I used there 60MB and 80MB product for the LRs I was producing while
working at Denali. (Used in micro VPN and wireless units, up through
large rackmount Sun UltraAXMP+ dual CPU based 8 x DS3 + 4 x 100Mbit
CBQ platform).
You treat setup just like an IDE drive system wise. They of course
are flash, and specced for something line a minimum of 10,000,000
rewrites for any sector, so using them as either a read-only root
device and creating your /var and writable areas in a ramdrive at
boot, or using them as the boot drive for a initrd 3 stage boot to
root ramdrive (what I normally do) is best.
Some of the early LRs with high function images had to ship running
direct off of the flash drive, with mods to reduce writes (expected
lifespan of the device 3 - 10 years for this use, but hard to do
right) due to issues in 2.2.x loading boot ramdries > 32M, but later
units were...
80MB bootable IDE flash drive, with 10 files. lilo.conf, 3
kernels, 2 configuration archives, 3 ramdrive images, and an initrd
2.88MB boot image.
One kernel/image and ramdrive image pair was the recovery set, never
to change and with hardwired configs (fairly small, without full
routing tools). It was just enough to boot, setup the network and
allow one to copy over the operational kernel and ramdisk packages.
The other 2 were changeable, so as to stage kernel/image or
configuration updates.
System hit lilo, did an initrd boot, loading and uncompressing the
chosen image into a 64MB ramdrive and copying in the configurations,
then finishing a normal boot. The flash drive was then remounted
under /flash to be available to the image management tools.
--
I route, therefore you are.
This archive was generated by hypermail 2a23 : Fri Mar 22 2002 - 15:33:27 AKST