From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthias Fouquet-Lapar Date: Mon, 27 Oct 2003 16:58:08 +0000 Subject: Re: [RFC] Better MCA recovery on IPF 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 Hi, my name is Matthias Fouquet-Lapar, I'm working in SGI's SW platform group mainly on CPU exception and error handling. As other members of this group, we're also looking into changing the Linux error handling to suit the needs of a reliable super-computer environment. I think error handling needs to be extended to not only recover from errors and kill for example the concerned application. Increasing chip density will increase the soft error rate, so it also becomes important to determinate if a error is soft (caused for example by cosmic rays) or if it is a true HW component failure requiring a replacement. There are also more complex error scenarios in multiple CPU environments when for example all CPUs access a cache line which has an error. Traditionally we're verifying our error handling by error injection as well as running tests with real, broken HW components for verification and regression testing. Obviously a lot of the error handling will be very platform dependant, but I think we should be able to come up with a common frame set. What do you think ? Thanks Matthias Fouquet-Lapar Core Platform Software mfl@sgi.com VNET 521-8213 Principal Engineer Silicon Graphics Home Office (+33) 1 3047 4127 > I want to make contributions to the development of MCA Error Handling. > > According to IPF Error Handling Guide, OS should have capability to recover from > error. > > There are three types of error, Corrected, Recoverable, and Fatal. They are > reported to OS by MCA/CPEI/CMCI, and actions required to OS depend on the type > of them. Relations between the type and the action are as follows; > > - Corrected: > Do nothing. > > - Recoverable: > Depends on the situation, > - Fix the error, continue interrupted thread. > - Terminate suffered threads. > - Just as Fatal, reboot. > > - Fatal: > Reboot system immediately. > > In all case, Linux should log error information based on SAL record. > So, some programs in user land, like fault prediction logic or > a daemon that reports error to remote site, could use these logs. And > system administrator also could use these logs to keep their system > healthy. > > > I have strong expectations for Linux to realize such recovery features. > However, Linux is deficient in recovery codes, especially on recoverable MCA, > at this moment. (I know your good job, Tony.) > > I want to know what difficulty keep Linux as-is. > > What do you think of error recovery on Linux? > What kind of functions, macros, structures should Linux have for recovery? > > > Best regards, > > ------ > > H.Seto