Re: Booting a modular kernel through a multiple streams file / Making Linux multiboot capable and grub loading kernel modules at boot time.

Eric W. Biederman
2001-12-19T09:33:24Z

"H. Peter Anvin" <hpa@zytor.com> writes:

> Eric W. Biederman wrote:
>
> > I have a personally dislike for using firmware calls to drive hardware
> > devices, so I won't be picking that up. But I am interested in what
> > it requires to not burn bridges. So I can make certain a linux kernel
> > loaded with a linux booting linux patch can requery the firmware.
> >
>
> > My impression is that the linux kernel already does the important
> > things by not smashing firmware reserved memory, (assuming you aren't
> > loaded with loadlin). So all that is required is to switch the idt
> > back to address 0, and switch the cpu back to 16bit real mode.
> > But if you know of other cases that need to be handled I would be
> > happy to hear about it.
> >
>
>
> Unfortunately that's not the case. The big issue is "who owns the interrupt
> controller", and "who owns the interrupts."
[snip]

> You can check out the BIOS extender I wrote for genesis at
> ftp://ftp.zytor.com/pub/linux/genesis/

Thanks. I've got genesis-1.10 now looking and digesting to see if you
have any unexpected tricks takes a little longer.

For my purposes I intend to fully disable the BIOS and then after I
have done all of my work, reenable the BIOS. Which should be a little
easier and have a slightly different set of issues.

>From the 10,000 foot level it looks like I am pretty safe already
except for those BIOS functions that drive the hardware. For those I
need to setup the legacy PIC back to it's default setting, and
possibly a few other hardware things. I wonder just how sensitive
the an x86 BIOS really is to changing those things...

For the most part I find it perfectly acceptable if I break all of the
firmware hardware drivers. As long as the information callbacks are
preserved. But preserver enough so I could load dos from linux would
be nice.

Eric