On Feb 18, 2009, at 9:36 PM, Ivan Warren wrote:
Now about Diag 250.. What's the gain ?
a) tons easier for the device driver writers. Take a look at the disk driver in OpenSolaris/z to see why I care.
Now.. Simplicity ? Device independence ? well, to support LPAR, you're going to have to deal with CCWs and device geometry anyway.
Yeah, but from my (non-Hercules, anyway) perspective, I don't really care about LPAR. The business case for running z/Linux in an LPAR is a very hard one to make. Now, it *is* nice if it works under Hercules because that opens up the development community to an order of magnitude more people. This is the cause of my apparent schizophrenia whereby I'm strongly suggesting that it would be neat if Hercules learned to do the (now fully documented) DIAGs that OpenSolaris requires and exploits.
The *only* gain I see is being able to leverage CP I/O Error Recovery Procedures - and logging (which you get on minidisks.. anyway ! even if issuing I/O to Minidisks with SSCH).
But, again, it makes writing the device driver a LOT easier. No need to screw around with error recovery in the driver--if it came back bad, you know the IO isn't going to succeed.
Of course, Adam (or anyone else), you are welcome (and encouraged) to prove me wrong :P
Plus, it provides orthogonality between ECKD and FBA: you don't have to care which you're dealing with. Just pick the right blocksize and away you go. Adam ---------------------------------------------------------------------- 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
