[LinuxBIOS] Support for recent chipset and powerful desktop CPU

[Segher Boessenkool]

>> Too late.
>
> Translation: LinuxBIOS cannot access the serial port on a PCI card
> until late in the boot process, after initializing and scanning the
> PCI bus. Only a serial port integrated into the mainboard chipset can
> be initialized early enough to be useful for debugging.

That's not exactly true.  A serial port that has its
address space subtractively decoded (at least at boot
time) certainly is easier to set up; but it certainly
isn't impossible to set up just enough of the PCI fan-out
to reach a plugin card; esp. if you do this for debug
purposes only (i.e., not for the end-user), you can
hardcode all of this.

But yes, it's very unfortunate "modern" systems are
so unfriendly to low-level bringup.  At the very least
it makes it really really hard to have some uniform
("generic") working early setup code.


Segher