Messages in this thread | | | Date | Thu, 30 Sep 1999 12:49:54 +1000 | From | Nathan Hand <> | Subject | Re: [Q]: Linux and real device drivers |
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On Tue, Sep 28, 1999 at 02:14:57PM -0400, tytso@mit.edu wrote: > Date: Mon, 27 Sep 1999 15:48:11 +0100 (BST) > From: Alan Cox <alan@lxorguk.ukuu.org.uk> > > > User buys Banavision capture card. Oops! Not supported in 2.2. User > > has to wait for the 2.4 kernel to come out (months and months > > away).... or use a development kernel. Whoops! 2.3 kernel has > > Come off it Ted, you know perfectly well we back port drivers as they become > stable - aggressively so. > > Yes, but (1) it takes time before they show up in the 2.2 releases, and > (2) does this really scale? Consider how many speciality devices are > out there --- from business card scanners to TV digitizing boards, etc. > Can you really keep up with all of the new devices? Remember, today > people can purchase these devices and they come with device driver disks > for Windows. Are we saying that there's something Windows can do that > we can't? That's embarassing.
Many drivers are appearing in user space anyway, often with truly token kernel support. Examples
- XFree86 (uses mmap and user space dma)
- SANE (uses scsi generic, perhaps ide-scsi emulation)
- cdrecord (uses scsi generic, perhaps ide-scsi emulation)
- ghostscript (de-facto printer drivers)
Locking the kernel interfaces down won't help any company coding binary only drivers for any of these projects.
My point: the "problem" is much broader than just the kernel. You can't save the world by locking down the Linux kernel driver interfaces.
> OK, so we don't want to lock down interfaces forever. I can accept > that. But do we really need to allow interfaces to arbitrarily change > during a stable kernel series? (Most of the times when we've need to > make such major changes to the stable kernel series, particularly during > the 2.0 series, stability has suffered.) I'd claim that it really isn't > that difficult to lock down internal interfaces during a stable kernel > release, and allow manufacturers to release device drivers that work > against 2.2 kernels. If they need to rewrite their drivers for the 2.4 > kernels, fine.
Every stability issue I've ever had with Linux has been traced to a bug in a driver. Binary only drivers would have meant adding kludges to the kernel to work around bugs in the drivers. No thanks. I want source for my driver, and if I have source, there's no problem changing interfaces and recompiling (someone will know how it's done).
My point: there's no such thing as a "stable kernel release" if drivers are available only in binary form. Drivers Needs Source.
ObReligiousArgument: whether everything needs source or not isn't worth arguing about, but drivers are too valuable to be binary only.
-- Nathan Hand - Chirp Web Design - http://www.chirp.com.au/ - $e^{i\pi}+1 = 0$ Phone: +61 2 6230 1871 Fax: +61 2 6230 1515 E-mail: nathanh@chirp.com.au
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