Re: How does PCIe appear to the host?

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>> If you're plugging in a card and it isn't seen, I'd check the BIOS
>> and look for any pcie settings it might have.
> I suspect it's worse than that in this case; see mlelstv's mail,
> explaining that there are only four lanes available total, so my
> "x16" slot is [actually x1 electrically]

I tried the card in another machine, in a "x16" slot.

It appears _that_ marking is honest in that respect:

ppb1 at pci0 dev 2 function 0: vendor 0x1022 product 0x9603 (rev. 0x00)
ppb1: PCI Express capability version 2 <Root Port of PCI-E Root Complex> x16 @ 5.0GT/s
ppb1: link is x2 @ 5.0GT/s
pci2 at ppb1 bus 2
pci2: i/o space, memory space enabled, rd/line, wr/inv ok
ahcisata0 at pci2 dev 0 function 0: vendor 0x197b product 0x0585
ahcisata0: interrupting at ioapic0 pin 18
ahcisata0: AHCI revision 0x10301, 5 ports, 32 command slots, features 0xef33e080
atabus0 at ahcisata0 channel 0
atabus1 at ahcisata0 channel 1
atabus2 at ahcisata0 channel 2
atabus3 at ahcisata0 channel 3
atabus4 at ahcisata0 channel 4
...
ahcisata0 port 2: device present, speed: 6.0Gb/s
wd0 at atabus2 drive 0: <WDC WD20EFRX-68EUZN0>
wd0: drive supports 16-sector PIO transfers, LBA48 addressing
wd0: HPA enabled, protected area present
wd0: limit not raised (not enabled in configuration)
wd0: 1863 GB, 3876021 cyl, 16 head, 63 sec, 512 bytes/sect x 3907029168 sectors
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133)
wd0: block sizes: medium 4096, interface 512, alignment 0
wd0(ahcisata0:2:0): using PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133) (using DMA)

Note (a) the ppb1: line says x16 (though it also says "link is x2"; if
I'm reading the code right this might mean the card actually requires
only x2, not x4, though it's x4 mechanically) and (b) ahcisata0 is
found, including the drive I had connected as a test.  So the card
appears fine.  I think mlelstv's explanation is (not surprisingly, in
view of whom it's from) right about why it doesn't work on the ASRock.

I also tried it in a "x8" slot, in a Dell PowerEdge 840.  This one is
more confusing, at least to me:

pchb0 at pci0 dev 0 function 0
pchb0: vendor 0x8086 product 0x2778 (rev. 0x00)
ppb0 at pci0 dev 1 function 0: vendor 0x8086 product 0x2779 (rev. 0x00)
ppb0: PCI Express capability version 1 <Root Port of PCI-E Root Complex> x8 @ 2.5GT/s
pci1 at ppb0 bus 1
pci1: i/o space, memory space enabled, rd/line, wr/inv ok
vendor 0x197b product 0x0585 (SATA mass storage, interface 0x01) at pci1 dev 0 function 0 not configured

It says it actually is x8, but then...not configured?  This is using
the same kernel as the above (each one was using my PXE boot setup,
just on different hardware), so I really want to figure out why the
same hardware - reported as same vendor/product, even recognized as
"SATA mass storage" - would fail to match on the second machine.  I
took that amchine out of service, but I can't now recall why; maybe
it's very slightly broken, returning the right vendor/product numbers
but trash in other fields?  I'll have to investigate.

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