CD bootcode

[rank1seeker at gmail.com]

----- Original Message -----
From: John Baldwin <jhb at freebsd.org>
To: freebsd-hackers at freebsd.org
Cc: rank1seeker at gmail.com
Date: Thu, 7 Jun 2012 08:21:39 -0400
Subject: Re: CD bootcode

> On Wednesday, June 06, 2012 12:15:14 pm rank1seeker at gmail.com wrote:
> > FreeBSD's CD bootcode '/boot/cdboot' is targeting stage 3 boot -> loader
> > For example, stage 2 boot '/boot/boot' is attempting the same.
> > 
> > In my case of a '/boot/loader', '/boot' is a symlink!
> > 
> > So if '/boot/boot' works with symlinks, why '/boot/cdboot' doesn't!
> > Yes, I did use Rock-Ridge extensions, upon creation of 'cd.iso'
> 
> Because I didn't make cdboot's lookup routine handle symlinks.  It
> also doesn't look at Rock-Ridge extensions and only uses the base
> ISO-9660 directory entries.  That was enough fun to write in assembly.
> OTOH, CD sectors are 2k, so you do have that much room to work with
> and can probably fit a more advanced directory lookup into cdboot.
> 
> I'm happy to review any patches you come up with.
> 
> -- 
> John Baldwin


I need to correct myself.
BOTH stage 2 boot '/boot/boot' AND '/boot/cdboot' don't work with symlinks!

'/boot/boot' on UFS sees symlink as file, same as '/boot/cdboot' does so on Rock-Ridge.

I can handle '/boot/boot' by providing full path to loader via 'boot.config'
'/boot/cdboot' doesn't have such a file, so in '/usr/src/sys/boot/i386/cdboot/cdboot.s':
--
loader_paths:   .asciz  "/BOOT/LOADER"
                .asciz  "/boot/loader"
                .byte 0
--

I injected third '.asciz' line with full path to 'loader' and recompiled it.
And what is first line "/BOOT/LOADER" doing in there ?!?

But even when loader is finally started, loader handles symlinks on UFS (kicked by '/boot/boot'), BUT fails so, on Rock-Ridge iso (kicked by '/boot/cdboot')
Looks like loader must be made into looking at Rock-Ridge extensions.

I can't provide patches, as I only know 'sh', 'php' (and web related langs)
Above code I've patched, only because I've hunted patterns.


Domagoj Smolčić