Date: Mon, 24 Aug 2009 22:09:07 +1000 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Ed Schouten <ed@FreeBSD.org> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r196506 - in head/sys: kern sys Message-ID: <20090824213600.T39644@delplex.bde.org> In-Reply-To: <200908241053.n7OArUhX092666@svn.freebsd.org> References: <200908241053.n7OArUhX092666@svn.freebsd.org>
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On Mon, 24 Aug 2009, Ed Schouten wrote: > Log: > Allow multiple console devices per driver without insane code duplication. > > Say, a driver wants to have multiple console devices to pick from, you > would normally write down something like this: > > CONSOLE_DRIVER(dev1); > CONSOLE_DRIVER(dev2); > > Unfortunately, this means that you have to declare 10 cn routines, > instead of 5. It also isn't possible to initialize cn_arg on beforehand. > > I noticed this restriction when I was implementing some of the console > bits for my vt(4) driver in my newcons branch. I have a single set of cn > routines (termcn_*) which are shared by all vt(4) console devices. > > In order to solve this, I'm adding a separate consdev_ops structure, > which contains all the function pointers. This structure is referenced > through consdev's cn_ops field. > > While there, I'm removing CONS_DRIVER() and cn_checkc, which have been > deprecated for years. They weren't used throughout the source, until the > Xen console driver showed up. CONSOLE_DRIVER() has been changed to do > the right thing. It now declares both the consdev and consdev_ops > structure and ties them together. In other words: this change doesn't > change the KPI for drivers that used the regular way of declaring > console devices. CONS_DRIVER() was a good interface, unlike CONSOLE_DRIVER(). Removing it completes the bitrot in the support for cn_dbctl, and completes removal of cn_checkc's good name at the driver level. cn_dbctl is still needed to unbreak sysctl's support for ddb (see db_main.c 1.4.2.1, which depends on cn_dbctl's infrastructure not having rotted) and can be used to unbreak polled i/o in all console drivers (not just in ddb mode -- it should have been named cn_ioctl) (see other mail). The higher level cngetc() and cncheckc() are still correctly named, now fully inconsistently with the driver level. Brucehelp
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