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    SubjectRe: legacy VGA device requirements (was: Exposing ROM's though sysfs)
    What should the API for this look like? We could add a VGA={0/1}
    attribute to all the VGA devices in sysfs.

    But then how do you:
    1) list all of the conflicting VGA devices in a domain?
    2) turn off all the VGA devices in a domain?

    We could build a bus like directory structure in /sys/class

    /sys/class/vga/domain1/vga1/(device/driver/enable)
    /sys/class/vga/domain1/vga2/(device/driver/enable)
    /sys/class/vga/domain2/vga1/(device/driver/enable)
    /sys/class/vga/domain2/vga2/(device/driver/enable)

    Then add an enable attribute in the domain directories that would shut
    off all of the subdevices.

    /sys/class/vga/domain1/enable
    /sys/class/vga/domain2/enable

    But the vga driver is not going to be attached to a device. Is there an
    easy way to build this is sysfs?

    --- Jesse Barnes <jbarnes@engr.sgi.com> wrote:

    > On Tuesday, August 3, 2004 5:59 pm, Benjamin Herrenschmidt wrote:
    > > All this could be very nicely dealt with by the kernel driver.
    >
    > So what requirements have we collected so far?
    >
    > o device selection (presumably domain, bus, slot, function)
    > i.e. select the device you'd like to manipulate
    > ioctl?
    > o per-domain & device VGA enable/disable
    > need to disable VGA ports on cards in the same domain and/or bus
    > ioctl?
    > o legacy port I/O
    > for properly routing I/O in multi-domain machines and machines
    > where the
    > kernel or firmware may need to trap master aborts
    > read/write?
    > o legacy memory mapping
    > for mapping the legacy VGA framebuffer, may fail
    > mmap?
    >
    > Is that a complete list? Of course, the interface mechanisms are up
    > for
    > debate too. We might be able to do it with per-bus or per-domain
    > files in
    > sysfs for the legacy I/O and memory stuff, but that might not
    > represent the
    > fact that legacy devices have interdependencies very well (e.g. VGA
    > ports
    > must be disabled on device A before we poke device B, etc.).
    >
    > Thanks,
    > Jesse
    >

    =====
    Jon Smirl
    jonsmirl@yahoo.com




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