Re: Early console attach vs PCI_NETBSD_CONFIGURE

[Michael <macallan%netbsd.org@localhost>]

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Hello,

On Aug 1, 2009, at 4:10 PM, Gavan Fantom wrote:

> I'm trying to find a good way to do early console attach on NetBSD/ 
> iyonix with a genfb-based console.

NetBSD/macppc uses an early rasops-based console.

> The graphics card is a NVidia GeForce2 MX which is supplied with the  
> machine, and there are drivers in flash for RISC OS, which boots  
> natively on the machine.
>
> NetBSD reconfigures the PCI bus early on during boot, so the base  
> addresses of the devices can and do move around from the way RISC OS  
> chose to lay out the bus.

Why do you reconfigure the bus? Any chance to leave the graphics card  
alone?

> The NetBSD bootloader passes enough information through about how  
> RISC OS has configured the card that we can attach genfb to it.

Look at macppc for a graphical console that works long before  
autoconfiguration.

> I'd like to attach the console early so that we can get early boot  
> messages appearing on the screen, but the problem is that if I do  
> that then the base address of the graphics card will move during  
> autoconfiguration and genfb will be left writing kernel messages to  
> memory which may not be backed by an actual framebuffer.

As I said - any way to avoid that? Otherwise you'd have to shut up the  
console during PCI reconfiguration and hand it the new fb address  
somehow.

> I can't see an obvious hook where I can reattach genfb with the new  
> address, and setup_memwins (in pci/pciconf.c) is peppered with calls  
> to printf guarded by pci_conf_debug. Given that after changing the  
> base address of the framebuffer and before reattaching the console a  
> printf could be fatal, I don't think simply reattaching after  
> pciconf has done its thing is enough.

When genfb at pci attaches the reconfiguration dance should be long  
done. You want something that works much earlier ;)

> I'm reluctant to add a hook that will be called immediately after  
> changing every single base address register, but that's the only way  
> I can think of right now.
>
> Is there a better way to do this?

If there is no output during PCI reconfiguration just add hooks right  
before and right after.
Why is it even necessary?

have fun
Michael

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