OT: PCI-X Bus Speed no set correctly on PE4600

Matt Domsch Matt_Domsch at dell.com
Thu Mar 6 07:38:00 CST 2003

On Thu, 2003-03-06 at 04:42, Marc Schmitt wrote:
> Hi all,
> According to the manual of the PE4600 it has:
> Hot-pluggable: 6 x 64-bit/100MHz PCI-X slots
> Yesterday I put in a QLA2310 FC adapter, which is a 64-bit/100MHz PCI-X 
> device. I placed it in slot 4 (bus 2) where no other device is that 
> could possibly force the bus to 66 MHz (slot 5 is empty). Indeed, in the 
> BIOS, the mode for slot 4 shows PCI-X, but the frequency is 66MHz 
> instead of 100MHz.

I really should go fix pciutils - I wrote that piece several years ago
before PCI-X existed.  It is actually running at 100MHz.

PCI-X spec says that cards can run at one of 2 speeds: 100MHz or
133MHz.  They always set the "66MHz" bit in config space (which is why
lspci shows this), but then looking at the PCI-X capabilities extension,
you see either 133MHz+ or 133MHz-.  Minus means 100Mhz, plus means
133MHz.  I agree it's not entirely clear from the lspci output.


Matt Domsch
Sr. Software Engineer, Lead Engineer, Architect
Dell Linux Solutions www.dell.com/linux
Linux on Dell mailing lists @ http://lists.us.dell.com

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