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SubjectRe: Add a "enable" sysfs attribute to the pci devices to allow userspace (Xorg) to enable devices without doing foul direct access
Date
On May 7, 2006, at 09:12:01, Pavel Machek wrote:
>>> It has everything to do with the 'enable' file. The 'enable' file
>>> lets you change the state of the hardware without an ownership
>>> mechanism. Other device users will not be notified of the state
>>> change. Since the other users can't be sure of the state of the
>>> hardware when they are activated, they will have to reload their
>>> state into the hardware on every activation.
>>
>> you seem to miss the fact that this can be done now without the
>> enable flag, setpci can be used to disable the BARs, again the
>> enable flag doesn't change that....
>
> ...well, when you launch setpci, you are firmly in 'unsupported'
> land. While 'enable' sounds like something where users expect it
> to be supported.

*Especially* since there are a number of users (including myself) who
have tendencies to go wandering around sysfs tinkering with the
available values. Not having seen this thread, I would have had no
problem doing "echo -n 0 >enable" on some device thinking that it was
a fairly standard way to turn off the power to my soundcard when I'm
not using it, and likely result in a kernel panic because I suddenly
disabled the BARs on the device out from under the driver.

Cheers,
Kyle Moffett

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