On Fri, 31 Aug 2001, Robert Warner wrote:
> Ok, I guess I have a little bit of a learning curve.
>
> Assumption: (please correct as necessary)
> The docipl just sets up the 'drive' access to the DOC. Then the remaining
> BIOS setup is performed by reading the information from the DOC.
Yes. The only addressable memory in DoC is the first 512 bytes, loaded
from the first 512 bytes of FLASH at power-up. This is the so called
docipl. This code is executed and sets up SDRAM and reads in blocks 2-127
from DoC to ram at 0x80000 (or less, if linuxbios is itself smaller than
that). This is what we call linuxbios.
We jump to 0x80000 and then the real work happens. Hardware (PCI) config,
etc., etc., to get the machine ready for linux, then we gunzip the kernel
from blocks 0x128-> size of kernel.
The kernel itself runs and in some cases mounts whatever is available from
DoC as root. On our cluster nodes we put docipl, linuxbios, and kernel
into the first 1Mbyte; then a mountable file system in the last 7 Mbytes.
> How 'big' does the DOC have to be (in a minimal since)?
It ought to be 1M, unless you want a file system on it ...
> Q: I would then use a 2nd DOC (or Harddisk) to boot the remaining LinuxOS?
Linux is booted out of doc. If you can fit your file system in 7M or less
(15M or less on the newer doc+), then use that for /. Otherwise you need
something else.
ron
