SGI VISWS support for 2.5

Hi all,

attached patch is a forward port of latest (2.4.17) visws patch from sourceforge. It's mostly trivial textual merge. Builds, unteseted.

Please take a look at it.

Andrey Panin            | Embedded systems software engineer
[email protected]        | PGP key: wwwkeys.eu.pgp.net

Thanks for doing this. I'm checking it out now on a 320.

Jesse

yeah!! I plan to port over the visw framebuffer soon. Care to try it out once your stuff gets merged into 2.5.X.

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I gave it a go on a 320 that I have here and it gets into start_kernel somewhere, but I don't get any output on the serial console. If you'd like to get it into 2.5, maybe we should clean it up a little first (as well as get it working)?

When I ported the last patch forward to 2.4.17, I noticed that there were quite a few parts that could use some work. Looking through the patch, it seems like the head.S stuff could be done in a better way, maybe a seperate head.S for machines that start in protected mode? Then again, maybe the boot loader should just be changed? The interrupt handler code also needs to be fixed up.

I haven't looked at the patch to seperate out i386 subarches yet, but maybe that would be a good first step to abstracting away some of the visws setup code?

Jesse

We definetely need to make it working and cleanup is a good thing too, but i dont have a VISWS (right now) so i'm limited to trivial mergework.

As far as i understand VISWS fragment in the head.S does 3 thing:
1) fills page tables;
2) twiddle some bits in cr3.
3) loads gdt and idt;
My small brain can't understand why we must do 1 and 3 so early. BTW looks like we are filling page tables many times (for every CPU). And why we move stext and _stext for VISWS ?
These are great mysteries ...

I'm doubtfull, does it worth the effort ?

2.5 with James's arch-split patch has most of VISWS code separated already. The only big trouble that remains is VISWS hacks in parse_mem_cmdline() function.

Also when 2.5 will realy use platform driver to support reboot, halt and power off, it will be possible to split VISWS code from process.c.

Andrey Panin            | Embedded systems software engineer
[email protected]        | PGP key: wwwkeys.eu.pgp.net