Messages in this thread | | | From | "Chris Jones" <> | Subject | RE: Dynamic Devices | Date | Sat, 9 Oct 1999 01:32:31 +0100 |
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Hi
> > method of having major,minor device files in /dev is going to have to > > go dynamic at some point or other (especially with the advent of hot > > Not true. You can map vast major/minors to files, you know.
But to accomodate vast major/minor combinations you have to increase the size of dev_t which (by your own words) will breaking everything. That sounds like too high a cost to me. > True. Use rm(1). Note "not used" is not the same as "device is not present > right now". F.ex, I want /dev/fd0 stay around if only to carry permissions > for floppies I insert into the drive.
Obviously, but I have a whole truck load of SCSI and goodness knows what else entries that I don't use because I don't own anything to connect to them. i didn't get any choice about those, my distro put them there. I could remove them, but the effort involved isn't really worth it. However, I would like it cleaned up (messy file systems piss me off ;) > Also note that the "callback to userland" scheme that was in the > kernel was scrapped some time ago as too fragile and too much overhead: > kerneld became kmod.
So scrap devfs and write kdevfs ;)
> I just don't get it. Even if you have to hack MAKEDEV to recognize modems, > and set them up with your defaults.
Wouldn't it be nicer to have it done for you? > The current scheme is totally transparent, without any extra crutches to > get it limping along. So it is a loose-loose situation.
It's largely transparent to new users because distros create hundreds of devices so that John Q Newbie will never have to worry his poor little head about mknod'ing or using MAKEDEV. That's not really transparent. It's not much of a big deal either. I don't think the issue here is really the average user and his need for a few devices here and there, but maximising the potential of the kernel. In the same way that a tiny fraction of linux users require 4GB ram support, but it has been put in, so, only a tiny fraction may need thousands of devices, but it should still be catered for (especially if it then makes the usage neater for everyone else). > I'm not arguing against devfs, I'm arguing against the idea that a dynamic > naming scheme for devices will magically manage your devices for you. It > just can't.
It's certainly a non-trivial problem, but it's not something that "can't" be done. > > I'm totally unbiased because I know nothing about the implementation > > of devfs or traditional devices, > > Then you can't know how much this costs, kernel-wise.
and yet you advocate changing the dev_t structure which you claim will break everything (and worse, it is userspace stuff). That sounds like a particularly horrific cost to me. > for i in 0 1 2 3 4 5; do > MAKEDEV usb$i > done > > is so hard that the kernel _must_ do it for you?
That is an oversimplified example that doesn't address the issues being discussed here.
- --- _____ _ _ _____ | __ | |___ ___| |_ ___| __|_ _ ___ Chris "Ng" Jones | __ -| | .'| _| '_|___|__ | | | | chris@black-sun.co.uk |_____|_|__,|___|_,_| |_____|___|_|_| www.black-sun.co.uk S o f t w a r e
"Linux is beating Windows" - David Cole, Microsoft Executive
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