[OpenBIOS] Exception 13 ?

[Ronald G. Minnich]

On Sat, 12 Feb 2000, Jeff Garzik wrote:

> Sure you can, as long as the right boot code is attached.  The final
> stage of the kernel build looks something like
> 
> 	make vmlinux
> 	make bootcode
> 	gzip -9 vmlinux
> 	cat bootcode vmlinux.gz > zImage

what a zimage is (in short): 
1) 512 bytes of floppy boot block
2) 2048 bytes of secondary boot block. 
3) linux kernel startup, with an uncompressed header and a compressed
image. The uncompressed header does the gunzip. Since we use openbios
gunzip, one of these two gunzips is useless and should be removed. For
linuxbios we opt to remove the linux kernel gunzip -- it's dead code after
boot, so why put it in? saves a few bytes. 

startup: 
If you're on floppy, the first 512 bytes are read, which reads the second
2048 bytes, which reads the kernel. The start of the kernel is some setup
and the 'unzipper'. 

If you're on hard drive the standard booters skip the first 512 bytes and
go for the secondary bootstrap. 

When we build a kernel for bios, we just compress vmlinux itself, minus
all the unzippers. I'm going to put this tree on the web page tomorrow. 


Sorry if this is too short, isdn is screwing me up again.

ron


-
To unsubscribe: send mail to majordomo at freiburg.linux.de
with 'unsubscribe openbios' in the body of the message