[LinuxBIOS] Support for recent chipset and powerful desktop CPU
segher at kernel.crashing.org
Thu Nov 30 04:19:26 CET 2006
>> 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.
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