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    SubjectRe: [patch 2.5] tg3.c: pci_{save,restore}_extended_state
    On Fri, Jan 24, 2003 at 03:34:02PM -0500, Jeff Garzik wrote:
    > On Fri, Jan 24, 2003 at 03:24:53PM -0500, Wiedemeier, Jeff wrote:
    > > On Fri, Jan 24, 2003 at 03:05:38PM -0500, Jeff Garzik wrote:
    > > If the intent is to just not use MSI on tg3 devices, I can use the pci
    > > quirks to make sure that MSI gets turned off for tg3 devices.
    >
    > hmmm, maybe I am missing something?

    Quoting section 6.8.1.3 of the PCI 2.2 spec (talking about message
    control in PCI config space):

    This register provides system software control over MSI. After reset,
    MSI is disabled (bit 0 is cleared) and the function requests servicing
    via its INTx# pin (if supported). System sofware can enable MSI by
    setting bit 0 of this register. System software is permitted to
    modify the Message Control register's read/write bits and fields.
    A device driver is not permitted to modify the Message Control
    register's read/write bits and fields.

    > AFAICS, this is a per-driver decision, and needs to be done at the
    > driver level, in the tg3 driver source.

    The last sentence in the quote above indicates that it is not intended
    (by the PCI spec) to be a per-driver decision, but rather a system
    decision. The messages used are also a per-bus system resource and how
    an MSI goes from the PCI bus to the rest of the system (i.e. the CPU(s))
    is implementation dependent.

    /jeff
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