Subject: Re: passing in the booted kernel name...?
To: Todd Vierling <email@example.com>
From: David Brownlee <firstname.lastname@example.org>
Date: 01/09/1999 19:20:40
On Sat, 9 Jan 1999, Todd Vierling wrote:
> How does this help you if you TFTP in your kernel? (Shark, for instance.
> Perhaps pmaxes too, who MOP in the kernel.)
> In general, `machdep.booted_kernel' can not really be made MI, and relying
> on it in the system is Bogus.
You fall back to /netbsd and are no worse off than now.
Some options, assuming we want to be able to boot alternative kernels.
1) Status Quo:
_Must_ have a copy of the booted kernel in /netbsd. Simplest
to implement, but least functional.
2) Pass in booted name from bootloader:
If kernel is on accessible filesystem, easy win.
If kernel is not accessible, we can look at the last component
of the name and look for that in the root directory. If we don't
find it we're no worse off, but it allows people to setup their
kernels so they can effectively boot alternative kernels.
If we cannot determine the name of the kernel, default back to
/netbsd, and we lose in no more cases than the current situation.
3) Boot loader loads necessary symbols, rc generates kvm.db, then kernel
releases memory. If symbols not found, fall back to one of the above
If the bootloader has support, we win (symbol wise) every time.
We waste some memory during early bootup. Could be a problem in
some memory poor machines, particlarly if booting single user.
The current situation loses when booting alternative kernels on all
machines. Option 2 wins with no effort on most machines, and allows
it to work with a little effort on the rest. Option 3 automatically
wins in more cases, but with the memory overhead during early boot.
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