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From: Jesse Barnes <jbarnes@engr.sgi.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: legacy VGA device requirements (was: Exposing ROM's though sysfs)
Date: Tue, 3 Aug 2004 18:18:02 -0700
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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