On Fri, Mar 07, 2008 at 01:02:47PM +0100, Zoltan Menyhart wrote: > Russ Anderson wrote: > > >Figure 2-1 does show SAL passing up CPEI records to OS, too. > > Yes, as I also said: > "The SAL / PAL can be the origin of CPEIs / CMCIs if they succeed > in correcting MCAs. They stock the related information until the > OS calls SAL_GET_STATE_INFO()." > > I Just want to emphasize that in case of the platform / CPU HW originated > CPEIs / CMCIs, the SAL does not know of them before we call > SAL_GET_STATE_INFO(), therefore it cannot store any information about > them. In some implementations SAL builds the records in response to SAL_GET_STATE_INFO(), in other implementations SAL knows of the CPEI/CMCI and builds/buffers the records before the SAL_GET_STATE_INFO() call. The SAL spec does not prohibit SAL building/buffering the records before SAL_GET_STATE_INFO(). >From a practical perspective, I don't think the difference significantly changes how linux should handle CPEIs/CMCIs. Linux should try to read/log the CPEI/CMCI as quick as possible. The lack of SAL buffering increases the chance of a record getting lost (overwritten) while SAL buffering reduces the chance that a CPEI/CMCI record gets lost (overwritten). If anything, the lack of SAL buffering would be a reason for more linux buffers, to reduce the chance of losing records. > >See section 5.3.2 CMC and CPE Records > > > > Each processor or physical platform could have multiple valid corrected > > machine check or corrected platform error records. The maximum number of > > these records present in a system depends on the SAL implementation and > > the storage space available on the system. There is no requirement for > > these records to be logged into NVM. The SAL may use an implementation > > specific error record replacement algorithm for overflow situations. The > > OS needs to make an explicit call to the SAL procedure > > SAL_CLEAR_STATE_INFO > > to clear the CMC and CPE records in order to free up the memory resources > > that may be used for future records. > > As far as I can understand, it is about the events not signaled by > interrupts, but MCAs, and either the PAL or the SAL manages to correct > them (=> CMCI, CPEI). Agreed that SAL corrected errors can get passed up as CMCI/CPEI. I do not believe it prohibits other CMCI/CPEI records from being built/buffered before the SAL_CLEAR_STATE_INFO() call. As stated above, from a practical perspective, I don't believe the difference significanlty changes how linux should behave other than possibly being a reason for more linux buffers. > You have got N >= 1 buffers for this kind of errors. My preference is for a larger N. Scaling N with system size may be the best solution for small & large systems. > >5.4.1 Corrected Error Event Record > > > > In response to a CMC/CPE condition, SAL builds and maintains the error > > record for OS retrieval. > > It does not say that the SAL knows about CMCI / CPEI signaled errors > before we call SAL_GET_STATE_INFO(). It does not say that SAL cannot know before the SAL_GET_STATE_INFO() call. > Example: the Tiger box with i82870: I take your word as how Tiger SAL behaves. Please take my word that other SAL implementations behave differently. Thanks, -- Russ Anderson, OS RAS/Partitioning Project Lead SGI - Silicon Graphics Inc rja@xxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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