From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bjorn Helgaas Date: Thu, 16 Nov 2006 16:28:01 +0000 Subject: Re: KDB blindly reads keyboard port Message-Id: <200611160928.02064.bjorn.helgaas@hp.com> List-Id: References: <23616.1163649739@kao2.melbourne.sgi.com> In-Reply-To: <23616.1163649739@kao2.melbourne.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Keith Owens Cc: linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org 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. Bjorn