On Wed, Sep 10, 2008 at 11:07:31PM -0700, vehemens wrote: > On Monday 08 September 2008 09:50:55 am vehemens wrote: > > On Monday 08 September 2008 06:41:53 am Robert Watson wrote: > > > On Mon, 8 Sep 2008, vehemens wrote: > > > > On Monday 08 September 2008 03:04:15 am Kostik Belousov wrote: > > > >> On Mon, Sep 08, 2008 at 02:02:00AM -0700, vehemens wrote: > > > >>> In linux drivers, there is a one to one relationship to an open and a > > > >>> calling argument structure called struct file. It provides a private > > > >>> data pointer that allows the driver to preserve unique state > > > >>> information across other calls such as read/write/ioctl/mmap/close > > > >>> etc. > > > >>> > > > >>> For bsd drivers, my understanding there is not an equivalent. As a > > > >>> result it is not possible to preserve different state information for > > > >>> multiple opens by the same thread of the same device major/minor #'s. > > > >>> > > > >>> Is this correct, or did i miss something? > > > >> > > > >> There is devfs_{get,set}_cdevpriv() KPI. Still no manpage, I shall fix > > > >> this ASAP. > > > > > > > > Just started looking at the firewire driver which has clone. It looks > > > > like it hooks into the event handler. > > > > > > > > Don't quite understand it all yet, so I'm going to look forward to that > > > > man page. > > > > > > Many device drivers continue to use the old clone interface, but are > > > gradually being converted over. You can look at the definitions and list > > > of converted drivers here: > > > > > > http://fxr.watson.org/fxr/ident?im=bigexcerpts;i=devfs_set_cdevpriv > > > > > > Looking at some of the converted drivers, I find myself a bit worried by > > > the extra error handling: in what situations do we expect that bpfioctl() > > > might be called without its cdev-private data? > > > > Got it now. Looks like the converted drivers are only in current, but the > > KPI is in at least 7.x as well. > > My first impression based on the modified drivers, was that I only needed to > add a get to open, and set's to ioctl, mmap, read, write, close etc. Also > that the data release would occur after the close call via the function > provided to get. I do not know whether this is an slip of keyboard, but most typically, you need set in open, and get in the read/write/mmap. > Don't have a problem with set, but some or all of the get's fail. I see > lot's of error=2 in ioctl, and error=9 in mmap, Going to instrument the code > next. Any suggestions would be helpful. > > On a side note, I had to first upgrade my 7.x system and was wondering if > there was a FreeBSD_version number for this feature? I do not remember, and in fact I do not see a reason for bumping version for this feature. In-tree drivers do not need the check, since they are in _the_ tree. Moreover, the cdevpriv does not change existing KPI, it only adds a bunch of functions. Increasing version for each KPI addition is rather pointless, IMHO. Also, see man(9) update at http://people.freebsd.org/~kib/misc/man9.1.patch that, among other items, contains start of the cdevpriv documentation.
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