Re: [XenPPC] [rfc] Serial discovery.

[Hollis Blanchard <hollisb@xxxxxxxxxx>]

On Mon, 2006-05-01 at 11:23 -0400, Jimi Xenidis wrote:
> Right now our serial device is assumed to be hanging off an ISA bus  
> (hardcoded address) at an offset (also hardcoded).
> Neglecting the IOMMU, the only devices that we are interested is  
> console.
> Right now we are restricting console to a UART, and have no plans to  
> support a framebuffer,ps/2,ADB,USB stuff tho it is possible (except  
> for USB :)).

I assume you mention these because xen/drivers/char/console.c uses the
IO accessors for VGA, e.g. inb(0x3da). Why should we write those off?

> Anyway, rather defining a bus+offset I think we should just keep an  
> absolute address for the UART.

What problem does this solve?

(It looks like ns16550.c may work with this change, but note the logic
in e.g. ns16550_init_preirq and ns_read_reg. The behavior of that driver
would change.)

If the issue is that you want to use inb/outb in a Zilog driver, please
use ioremap (even though it's a no-op) and readb/writeb instead, like
ns16550.c.

-- 
Hollis Blanchard
IBM Linux Technology Center


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