Date: Tue, 14 Nov 2006 20:23:55 -0800 From: "Matthew Jacob" <lydianconcepts@gmail.com> To: freebsd-scsi@freebsd.org Subject: basic domain validation patches- 3rd and final call Message-ID: <7579f7fb0611142023l614c0d3bj4559c0b26b5817b8@mail.gmail.com>
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Please review, or these will be going in as the basis for ongoing work. They aren't perfect, but I believe that they are a sorely needed start. Speak now or forever hold your piece. On 11/2/06, mjacob@freebsd.org <mjacob@freebsd.org> wrote: > > See http://people.freebsd.org/~mjacob/DV_PATCHES > > The ANSI document on Domain Validation gives an algorithm for doing > Basic Domain Validation as, in part: > > Send an INQUIRY command to a SCSI device 3 times- twice with the > default transfer agreement and once with the transfer agreement set > to the fastest supported values. The Basic test fails when the first > 36 bytes of data returned at the negotiated synchronous speed does not > match the data received at the asynchronous transfer speed. In > addition, the Basic test fails if a CRC error (or parity error for > non-DT clocking) or a timeout occurs. If data miscompare occurs, the > test should be repeated (e.g., this could be due to the target changing > INQUIRY data during SCSI device initialization). After a finite number > of retries, if data miscompare recurs then fall-back should be > attempted (see 5.5.2). > > and 5.5.2 has: > > If Basic or Enhanced tests fail, a fall-back setting is set and the > tests are performed again. The recommended fall-back order is: > > 1. fast-160 > 2. fast-80 > 3. fast-40 (with DT clocking enabled) > 4. fast-40 (with ST clocking enabled) > 5. fast-20 > 6. fast-10; and > 7. asynchrnous transfer. > > I've done an implementation interwoven into the probe code in cam_xpt > such that the following occurs.. > > The normal sequence is: > > ... > INQUIRY (short) > INQUIRY (long) > ... > ('default' sync settings are enabled) > ... > PROBE_TUR_FOR_NEGOTIATION > <END> > > I've changed <END> to be: > > PROBE_TUR_FOR_NEGOTIATION > PROBE_INQUIRY_BASIC_DV1 > ... > PROBE_INQUIRY_BASIC_DV2 > ... > > The idea here is to leverage the two initial INQUIRY commands done at > async mode and compare with the last known one and to do *two* > additional INQUIRY commands (at speed) to see if they compare with the > last ASYNC long INQUIRY command. If they don't, we can do backoff and > just re-enter the state machine at PROBE_TUR_FOR_NEGOTIATION. > > The backoff doesn't do DT/ST settings, but just simply increments the > sync_period factor until we hit 0xf (5 MHz) and then drops to async. > > I don't mess with PPR settings on the theory that the SIM will do the > right thing with PPR settings depending on the values of sync period and > offset. > > By doing fault injection (e..g, failed compares) I've done some testing > and this *appears* to do what one would want. > > Any comments? I *know* there are people out there on this list who have > more experience with DV than I do so I'd appreciate some comments. > > -matt > > > > > _______________________________________________ > freebsd-scsi@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-scsi > To unsubscribe, send any mail to "freebsd-scsi-unsubscribe@freebsd.org" >
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