> >> I am looking for a place where I can see the active cmma setting. I can't > >> find it in either /sys or /proc. Am I looking in the wrong place or is > >> there no such thing? I seems that with SLES10SP1 the ipl default was > >> changed from cmma=off to cmma=on but I am looking for confirmation of this. > > >There is no user space interface within Linux to figure out if cmma is > >active or not. > >The default for SLES10SP1 should be off. However you can verify this by > >issuing the CP command "QUERY MEMASSIST". If it responses with status > >ACTIVE then cmma is active. > >Please have a look at the CP Commands and Utilities Reference for > >further details. > I am working with Rob vd Heij. We found out that Q MEMASSIST does not > indicate whether Linux is actually using cmma. An ESSA instruction seems > to be done regardless of the cmma= ipl parm, making CP believe the guest > will be using cmma. But when cmma= defaults or is specified off then the > kernel will not do so. This split view between CP and the Linux kernel > seems broken to me.
Oh yes, you're absolutely right. Linux issues the ESSA instruction once to figure out if it will work or not (program check or not), just to tell later if the kernel paramater cmma=... makes any sense. So there's no way z/VM could know if Linux is actually using cmma or if it was just a test. This can be done better by e.g. doing the test later after the kernel parameter has been parsed. On the other side I'm quite sure there must be a feature flag somewhere which indicates if the ESSA instruction works or not. Testing feature flags should be the method to go anyway. Thanks for figuring this out! ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
