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? Robert N M Watson Computer Laboratory University of CambridgeReceived on Mon Sep 08 2008 - 11:41:56 UTC
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