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Re: Help with i386 OBSD booting/kernel-init setup please



Making, drinking tea and reading an opus magnum from Tobias Weingartner:
> > I have a devlopment version of SF that net-boots and runs sufficiently
> > to load an OpenBSD i386 kernel using bootp/tftp and then try to launch
> > it.  Right now I'm simply trying to get it to get past device probing
> > and either panic due to no boot disk, or try to boot off of the net.
> 
> This is quite far.  If you take a look at the current /boot sources for
> the x86 arch, you should be able to find all you need to know about loading
> and invoking a kernel.  For the most part, it's pretty straight forward.
> 
> There are basically 4 things you need to do, to have obsd boot successfully;
> 1) Load kernel at physical 1MB in RAM.
> 2) Setup registers + Stack as in /boot.
> 3) Pass all needed BIOSargs that current /boot passes to the kernel.
> 4) Pray.  Jump to kernel init.  :-)
> 
> I'm guessing that you are missing out on the #3 department.  In particular,
> chances are that you are not passing the kernel anything about the amount of
> RAM that is has available, etc.
th #3 is no completely true.
none of the information provided in the bootargs is critical for kernel boot.
i.e. memmap is not used right no in -current.
apminfo is not critical too, as well as pciinfo.
diskinfo might be usefull, but not to actually just boot the kernel.
could be of course that some dependancies actually got established somewhere.

> > Naturally, since this is PC hardware, things are not anywhere near being
> > simple.  The OBSD kernel boots, displays its first copyright messages on
> > the console, then immediately faults or hard-resets the machine.
> 
> I'm guessing that there is a "problem" with the kernel not knowing how much
> memory (not having a memory map passed to it) it has to deal with.
no, cnvmem and extmem were passed in, which is enough for -current kernels.

> Basically, the kernel expects to be invoked in 32-bit mode, VM disabled.  Other
> than that, the above 4 points should help somewhat.
VM is not disabled, VM is setup in kinda linear mode so be speaking.

> To help with the bad parts, think and drink Guiness...  :-)
w/ a shot of smth, really helps to open borders of reality (;

cu

-- 
    paranoic mickey       (my employers have changed but, the name has remained)