Re: legacy VGA device requirements (was: Exposing ROM's though sysfs)

From: Jesse Barnes
Date: Tue Aug 03 2004 - 20:21:18 EST


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
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