Date: Sat, 11 Sep 2010 07:55:36 -0400 From: John Baldwin <jhb@FreeBSD.org> To: perryh@pluto.rain.com Cc: freebsd-stable@freebsd.org Subject: Re: MSIX failure Message-ID: <4C8B6E38.7030303@FreeBSD.org> In-Reply-To: <4c8b3777.A5l69BLBx5dsBnNl%perryh@pluto.rain.com> References: <AANLkTikvd09fw3fUhxsXDhMoWE-kvMoPjXPSTfzYY73T@mail.gmail.com> <20100909150012.GA27370@lordcow.org> <4c89d653.UyUz1Sv9zPckJnig%perryh@pluto.rain.com> <201009100757.49777.jhb@freebsd.org> <4c8b3777.A5l69BLBx5dsBnNl%perryh@pluto.rain.com>
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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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