Re: KDB blindly reads keyboard port

From: Bjorn Helgaas <>
Date: 2006-11-17 03:28:01
On Wednesday 15 November 2006 21:02, Keith Owens wrote:
> I implemented this in my kdb tree, but it has a very nasty side effect,
> it stops you from debugging that part of the boot process between kdb
> startup and when the i8042 is probed.  KDB starts up very early so we
> can debug the boot process.  Not being able to use the PC keyboard
> until later in boot is not acceptable.  People using USB keyboards
> already suffer from this problem and it is very frustrating.
> Adding a "kdb_use_keyboard" flag means all existing systems have to
> change if they want a debugger during boot, just to workaround a few
> systems that get an error when reading from non-existent legacy I/O
> ports.  So I am going back to my original idea, add 'kdb_skip_keyboard'
> which is only required on the problem machines.

Hold on a minute.  These "problem machines" are completely compliant
with all the relevant ia64 specs in this area.  There is no spec that
says a keyboard controller must be present or that reading a non-
existent I/O port should be safe.

What about the FADT iapc_boot_arch bit?  Did you determine that isn't
sufficient for some reason?  That's available very early.

To unsubscribe from this list: send the line "unsubscribe linux-ia64" in
the body of a message to
More majordomo info at
Received on Fri Nov 17 03:28:20 2006

This archive was generated by hypermail 2.1.8 : 2006-11-17 03:28:32 EST