Re: [patch] early printk and boot console fixups.

From: Yinghai Lu
Date: Wed May 16 2007 - 12:29:21 EST


On 5/16/07, Bjorn Helgaas <bjorn.helgaas@xxxxxx> wrote:
On Tuesday 15 May 2007 10:17:50 pm Yinghai Lu wrote:
> for early_uart_console, I have some ideas:
> 1. merged that into early_serial_console in
> arch/x86_64/kernel/early_printk.c, and
> move early_printk.c to kernel/, --- make it understand
> earlyprintk=uart,io,0x3f8,9600n8
> earlyprintk=uart,mmio,0xff5e0000,115200n8
> in addition to vga, ttyS, serial

I would rather try to merge 8250_early and early_printk.
"console=uart,io,0x3f8" is already pretty similar to
"earlyprintk=serial", and it would be nice to have only one.

"console=uart" does have the disadvantage that you have to know the
port address. But it has the advantage that it doesn't depend on
compiled-in legacy serial port names. If you need early console
output, you're probably a developer and can come up with the address.

I think it would be nice to have a "console=vga". That could use
the current "earlyprintk=vga" implementation, and automatically
hand off to tty0.

Then we could remove "earlyprintk=" and always use "console=uart"
or "console=vga".

earlyprintk= is needed for seeting bootconsole, or setting CON_BOOT,
and it is could be loaded earlier with early_param than console_init.

in the console_init (via register_console), the console is handed over
from bootconsole to normal console.

also console_init could be moved to quite late than current, and till
some subsystem is initialized like pci and usb.

YH
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