From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Luck, Tony" Date: Tue, 18 Nov 2003 17:47:41 +0000 Subject: RE: [RFC] How drivers notice a MCA on I/O read? [1/3] Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org > This would not only be useful for the occasional device failure, but > also for accessing memory spaces which by definition may or may not > respond to PIO requets, like legacy I/O bus and memory regions. Upon > entering readb_check(), you could set a global telling the MCA handler > to potentially expect a failure from the address or range that was > passed in. This would allow the MCA handler describe in simple terms > what went wrong in case of failure and/or take appropriate action. As Zoltan mentioned in his mail you'd have to do some heavy fencing around the internals of readb_check() to make this safe ... which might make readb_check() too expensive to use for the 99.999999% of the cases where the I/O board isn't broken. But I don't actually know how much overhead would be involved ... I/O reads are already horrendously slow, so you may be able to add some sizeable overhead without affecting macro benchmarks more than a few percent. -Tony