perryh@pluto.rain.com wrote:
> John Baldwin <jhb@freebsd.org> wrote:
>> On Friday, September 10, 2010 2:55:15 am perryh@pluto.rain.com wrote:
>>> ...
>>> It is arguably a bug to open O_RDWR when only examining things.
>> You have to have RDWR permission to issue the ioctl to read config
>> registers which pciconf does when examining capabilities.
>
> So much for avoiding a reboot for <bsd@lordcow.org> (or whatever the
> correct address is -- that one bounced), but now it is beginning to
> look as if there may be a POLA violation at a lower level. Unless
> there are devices out there whose state can be changed by merely
> _reading_ (not writing) their configuration registers, I would not
> expect to need RDWR permission just to read them.
Umm, not all config registers are standardized and devices are free to
define device-specific registers with device-specific behavior (many
do). Given that, it is quite possible for a device to implement a
register that takes action when read (e.g. resets to 0 or clears status
bits, etc.).
pciconf -l itself does not require RDWR permissions, only -c which does
a good bit more work.
--
John Baldwin
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