Messages in this thread | | | Date | Fri, 9 Jun 2006 21:37:52 -0700 | From | Greg KH <> | Subject | Re: [PATCH 2/5] VT binding: Add sysfs support |
| |
On Sat, Jun 10, 2006 at 08:38:18AM +0800, Antonino A. Daplas wrote: > Greg KH wrote: > > On Fri, Jun 09, 2006 at 04:39:51PM +0800, Antonino A. Daplas wrote: > >> Add sysfs attributes for binding and unbinding VT console drivers. The > >> attributes are located in /sys/class/tty/console and are namely: > >> > >> A. backend - list registered drivers in the following format: > >> > >> "I C: Description" > > > > No, this violates the "one value per file" issue with sysfs. How do you > > know you will not overflow the buffer passed to you? > > I was wondering about this. I just want a way to show what are the currently > loaded drivers, so it's a read-only attribute. It's using snprintf (though > I haven't added a check for possible overflows, should be a 2-liner). Maximum > number of lines is 16, and there are examples of this rule-breakage in the > current sysfs tree. > > /sys/class/usb_host/usb_hostx/device/pools
Ah, thanks for pointing this out. Those files should go to debugfs, they do NOT belong in sysfs at all.
> Yes, none are valid excuses. Anyway, what would be the best way? I was > considering creating another class for vt_console, but that would entail > the creation of a new device major number just for this.
No, you don't need a major to create a new class in sysfs at all. Look at usb_host for an example of that :)
And even if you did, we have loads of free major numbers now, it's not a big deal to get a new one.
I vote for this, it would make things much easier.
> >> Where: I = ID number of the driver > >> C = status of the driver which can be: > >> > >> S = system driver > >> B = bound modular driver > >> U = unbound modular driver > >> > >> Description - text description of the driver > >> > >> B. bind - binds a driver to the console layer > >> > >> echo <ID> > /sys/class/tty/console/bind > >> > >> C. unbind - unbinds a driver from the console layer > >> > >> echo <ID> > /sys/class/tty/console/unbind > >> > >> The tty layer does nothing to these attributes except create them and punt all > >> requests to the VT layer. > > > > Why is this needed? What is wrong with the current scheme of binding > > ttys to the console? > > > > The binding part, maybe none, but that's still debatable. It's the unbinding > feature that people are requesting. Note the longish threads on "the future > of graphics subsystem". It would also ease the life of console driver > developers, and it would stop people from pestering me on why they cannot unload > their beloved framebuffer console and drivers and go back to VGA console.
Ok, I also read the 0/5 in this series which describes this in detail, sorry for not seeing that (hint, cc: everyone on the series that one too, so they get a bit of detail in the future.)
thanks,
greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |