Subject: Re: booting from CD
To: Uwe Lienig <>
From: Simon Burge <>
List: port-pmax
Date: 03/31/2000 00:13:56
Uwe Lienig wrote:

> AFAIK, you are out of luck. DECstation's no matter of their type won't
> boot off a CD-ROM with a CDFS (iso whatever) on it. The problem lies in
> the bootprom, which assumes, that the blocksize of the cdrom is 512
> bytes (which isn't true for CD-ROMs using CDFS). If anybody knows, how
> to get around this problem, let me know ...

It's true that an ISO9660 filesystem is layed out in terms of 2048 byte
blocks, but the PROM only knows that it needs to load the first stage
boot blocks from a certain 512 byte sector range - it doesn't care where
in the 2048 byte logical blocks where these sectors are.  This first
stage is then smart enough to find the second stage on the CDFS and the
second stage loads the kernel.  We (well, not me - I don't have a burner
but Philip Tait tested some images I made) have successfully booted
CD-ROMs on DECstations that have ISO9660 filesystems.