[My apologies if this is the wrong mailing list for this, but it seemed to be the most relevant. Please direct me elsewhere and discard if this is OT.] Hi all, I've been beating my head against SGPIO for a bit now, and I can't tell if I'm just misreading SFF-8485, or this backplane is just not doing something sane. I have here a Supermicro X8DAH-F+ with a backplane of model BPN-SAS-836A - which means it has 3 MG9072 controller chips on it. Supports speaking in-band or out-of-band to read data, control lights, &c. With two LSI 9201-16i HBA attached, manipulating it via /dev/bsg/sas_hostN and smp_utils 0.97, SFF-8485 section 8.4.4 seems to think that changing this: 00 41 02 00 00 a0 a0 a0 a0 a0 a0 a0 a0 a0 a0 a0 a0 10 a0 a0 a0 a0 00 00 00 00 00 00 00 00 00 00 00 00 20 00 00 00 00 By doing this: # smp_write_gpio -d a1,a0,a0,a0 -t 3 -i 0 -c /dev/bsg/sas_hostN Resulting in: 00 41 02 00 00 a1 a0 a0 a0 a0 a0 a0 a0 a0 a0 a0 a0 10 a0 a0 a0 a0 00 00 00 00 00 00 00 00 00 00 00 00 20 00 00 00 00 Should enable a single drive's fault LED (drive m+3, by spec above). In practice, I am in possession of ~90 identical machines, and on every single one, this controls the fault LED on 3 drives - I have 3 SAS ports wired to the backplane (via iPASS cable) per HBA, so I would suspect the HBA of setting bit m+3 on each SAS port [and having each of its three ports running to an input controlled by a different SGPIO controller on the backplane]. No permutation of the register bits beyond the 4 bytes at index 0 changes the behavior of the LEDs that I can see, and the output in the beginning [a0 a0 ... 00 00 00 00] is what is returned on clean cold boot of the machine. In contrast, when I have an LSI 9240-8i attached, I can control per-drive LEDs, though the mechanism it uses for this is opaque to me (the megaraid_sas driver doesn't expose a virtual SAS host port like mpt2sas, so I am manipulating this using LSI's closed-source MegaCli blob); so I know it is possible, through some method, to control per-drive LEDs. I cannot tell, however, whether I am using smp_write_gpio incorrectly (either by misreading the spec or somehow abusing the virtual SAS port), or it's a bug somewhere (be it in smp_write_gpio, the kernel, the HBA firmware, or the upstream MG9072's firmware, that is somehow magically avoided by the 9240-8i), and there is almost no public documentation of people using smp_write_gpio. I've tried this with kernel 2.6.32-220.7.1.el6, 3.4.4, and 3.5.0-rc5 (the last because it includes mpt2sas 13.XX.XX.XX, while 3.4.4 has 12.XX.XX.XX, and I was curious if anything had changed), and smp_utils 0.97. I wanted to see what the register state was when the 9240-8i was in use, but I couldn't coax the megaraid_sas driver into disgorging this information, and upon unplugging the iPASS cable from the backplane to connect it to the HBA, the backplane appears to reset its internal state; the LEDs cease blinking in any pattern, and consequent querying with the HBA returns expected default initial state. Am I insane, or is this backplane crazy? Does anyone have any experience with cajoling such things into submission? Thanks, - Rich Ercolani -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
