Re: [linux-pm] [RFC/RFT][PATCH -mm 2/5] swsusp: userland interface (rev. 2)

[Greg KH]

On Thu, Jan 05, 2006 at 01:18:37AM +0100, Pavel Machek wrote:
> Hi!
> 
> > > +static int __init snapshot_dev_init(void)
> > > +{
> > > +	int error;
> > > +
> > > +	error =  alloc_chrdev_region(&interface.devno, 0, 1, interface.name);
> > > +	if (error)
> > > +		return error;
> > > +	cdev_init(&interface.cdev, &snapshot_fops);
> > > +	interface.cdev.ops = &snapshot_fops;
> > > +	error = cdev_add(&interface.cdev, interface.devno, 1);
> > > +	if (error)
> > > +		goto Unregister;
> > > +	error = sysfs_create_file(&power_subsys.kset.kobj, &snapshot_attr.attr);
> > 
> > Heh, that's a neat hack, register a sysfs file that contains the
> > major:minor (there is a function that will print that the correct way,
> > if you really want to do that), in sysfs.  It's better to just register
> > a misc character device with the name "snapshot", and then udev will
> > create your userspace node with the proper major:minor all automatically
> > for you.
> > 
> > Unless you want to turn these into syscalls :)
> 
> Well, I think we simply want to get static major/minor allocated for
> this device. It really uses read/write, IIRC, so no, I do not think we
> want to make it a syscall.

Ok, then I'd recommend using the misc device, dynamic for now, and
reserve one when you get a bit closer to merging into mainline.

thanks,

greg k-h
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