On Mon, 25 Jun 2012 09:44:08 -0400 J R <[email protected]> wrote:
:>The ENQ portion of the RESERVE macro goes ahead as usual. :>The reserve bit in the UCB is only set if the ENQ is successful. :>The RESERVE macro implies IO to the device. If there is no IO :>before the subsequent DEQ, the hardware reserve doesn't need to be issued. My issue is that the I/O can be issued and be blocked because the device is reserved to another system. By issuing a conditional ENQ, one wishes an indication that the resource is not immediately available so that other actions can be taken. If that is the way it works, so be it, but it seems wrong to me. :>> Date: Mon, 25 Jun 2012 16:33:17 +0300 :>> From: [email protected] :>> Subject: Re: Why is GRS ENQ needed in SMFDUMP program? :>> To: [email protected] :>> :>> On Mon, 25 Jun 2012 09:25:02 -0400 J R <[email protected]> wrote: :>> :>> :>The RESERVE macro did (still does?) not directly do the hardware reserve. :>> :>Rather, it set a bit in the UCB to tell the next IO to the unit to prepend :>> :>a reserve CCW to the channel program. :>> :>> How would that work with a conditional reserve? How can the O/S know if the :>> reserve can be satisfied unless the reserve I/O is complete? -- Binyamin Dissen <[email protected]> http://www.dissensoftware.com Director, Dissen Software, Bar & Grill - Israel Should you use the mailblocks package and expect a response from me, you should preauthorize the dissensoftware.com domain. I very rarely bother responding to challenge/response systems, especially those from irresponsible companies. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
