On Tuesday, 08/14/2012 at 02:50 EDT, Neale Ferguson <ne...@sinenomine.net> wrote: > Is it signficant that the INT-PARM is 0 - probably set when device is > online? Compare this to an active disk: > > SCHIB DEV INT-PARM ISC FLG LP PNO LPU PI MBI PO PA CHPID0-3 CHPID4-7 > 0007 0201 1F7EB400 3 87 80 00 80 80 0000 FF 80 EF000000 00000000
When a subchannel first appears, the OS will typically issue Modify Subchannel to change the interrupt parameter to reflect the address of a device control block or I/O scheduling element. But until then, the interrupt parm is zero. (LINK and DETACH don't generate I/O interrupts, but they will cause channel-report-pending machine checks.) Because subchannel IDs (e.g. 0007) are "dense", they are re-used. That is, if you detach 201 and link something else, it will be added using subchannel 7. If Linux keeps any residual fingerprints based on subchannel id, it could get confused. But I would think that such errors would have been flushed out years ago. Alan Altmark Senior Managing z/VM and Linux Consultant IBM System Lab Services and Training ibm.com/systems/services/labservices office: 607.429.3323 mobile; 607.321.7556 alan_altm...@us.ibm.com IBM Endicott ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
