Re: How does PCIe appear to the host?

[Brian Buhrow <buhrow%nfbcal.org@localhost>]

	hello.  It's been my experience that pcie busses show up as pci busses from the software
perspective and, as you note, simply have more capabilities than standard pci connections.  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.  Typically they're under the advanced south bridge configuration section, but
BIOS's vary and you'll probably have to crawl through the menus to find it.

	Once you think you have things turned on, I'd use pcictl to try and get a list ing of all
the busses and devices the OS sees.  You don't say which version of NetBSD you're running, but
I've used pcie as early as NetBSD-3 and quite extensively on  NetBSD-5.  

	Other trivia I've picked up over the years:

	Cards usually probe in order from the PCI/PCIE  slot closest to the power supply/connector
outward.  

	You might experiment by booting without ACPI to see how the PCI busses probe in that case.

Older versions of NetBSD don't seem to do anything with speed settings, so you won't get any
mentions of speed transfers or the like on NetBSD-5.

	If the PCIE card you're using is working properly, it should be seen by the BIOS as
additional SATA ports.  If you have a drive plugged into it when you boot the BIOS, you might
even be rewarded with a listing of the make and model of the drive you have connected.  If you
see that, you then know it's not hardware trouble.

Hope that helps.
-Brian
On Oct 3,  1:13am, Mouse wrote:
} Subject: How does PCIe appear to the host?
} How does PCIe differ from PCI from the CPU's point of view?  I'm
} running into an issue and it seems to me this is important.
} 
} I've been having hardware (partially) fail on me recently, which is
} breaking my backups.  In particular, I'm having trouble finding a
} machine to connect the backup disks to - they're SATA, and I don't have
} very many machines with SATA, and some of those SATA ports appear to be
} broken (one machine, for example, has six, of which I've been able to
} make only two work).
} 
} One of these machines is an ASRock Q1900M.  It has only two SATA ports
} onboard; it has two PCIe x1 slots and a PCIe x16 slot.  I just today
} picked up a 5-port PCIe SATA card and tried it.
} 
} The reason I'm asking about PCIe is that, as far as I can tell from the
} host, it isn't there at all.  While this is a relatively old kernel,
} I'd expect at least a "not configured" line - but dmesg is identical
} between a boot with it and a boot without it.  So now I'm wondering
} whether I've got a DOA card, or a duff slot, or I need to backport
} something, or whether this is somehow expected, or what.
} 
} I've already backported the printout of PCIe capability in ppb.c.  The
} ppbs report as
} 
} ppb0: PCI Express capability version 2 <Root Port of PCI-E Root Complex> x1 @ 5.0GT/s
} pci1 at ppb0 bus 1
} pci1: i/o space, memory space enabled, rd/line, wr/inv ok
} ppb1 at pci0 dev 28 function 1: vendor 0x8086 product 0x0f4a (rev. 0x0e)
} ppb1: PCI Express capability version 2 <Root Port of PCI-E Root Complex> x1 @ 5.0GT/s
} pci2 at ppb1 bus 2
} pci2: i/o space, memory space enabled, rd/line, wr/inv ok
} ppb2 at pci0 dev 28 function 2: vendor 0x8086 product 0x0f4c (rev. 0x0e)
} ppb2: PCI Express capability version 2 <Root Port of PCI-E Root Complex> x1 @ 5.0GT/s
} pci3 at ppb2 bus 3
} pci3: i/o space, memory space enabled, rd/line, wr/inv ok
} ppb3 at pci0 dev 28 function 3: vendor 0x8086 product 0x0f4e (rev. 0x0e)
} ppb3: PCI Express capability version 2 <Root Port of PCI-E Root Complex> x1 @ 5.0GT/s
} 
} I note a possible conflict between the "x1" and the presence of a x16
} slot; that 1 is coming from the PCIE_LCAP_MAX_WIDTH bits in PCIE_LCAP,
} which makes me wonder whether something needs configuring to run the
} x16 slot at more than x1.  The card does say it needs a x4 or higher
} slot to work, so if the x16 slot is running x1 (is that even possible?)
} that might be responsible.
} 
} Any thoughts?  Any pointers to where I might usefully look?
} 
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