Re: Direct access to hardware

From: Stephen Frost (sfrost@ns.snowman.net)
Date: Tue Jul 25 2000 - 11:44:20 EST


On Tue, 25 Jul 2000, James Sutherland wrote:

> On Tue, 25 Jul 2000, Stephen Frost wrote:
>
> > We *don't* do *everything* in userland. We just allow access to
> > the raw side of the world from userland so that a program doesn't have
> > to do worse things to try and get the same access. The way it currently
> > is there is the possibility that a vendor wouldn't have to muck around
> > in the kernel to be able to upgrade the flash.
>
> Making that sort of thing available to userland is not a good idea, IMO.

        It's already availible, as others have mentioned. There are other
ways to do it, this just provides a nice clean way instead of horrible
hacks.

> Apart from anything else, I do NOT want to see Linux tools for upgrading
> firmware etc. for exactly the same reasons I don't want to see Windows
> ones: Why assume/require that I am running Linux or Windows?
>
> A vendor supplied bootdisk is completely OS neutral, since the OS is out
> of the equation. I could use that bootdisk whether my main OS is Linux,
> NT, FreeBSD, Netware, whatever I want.

        In the end, mainly this is because of the attempts to make it
simple for the users.

> > This keeps the vendor specific *junk* out of the kernel and in
> > userland.
>
> I'd rather keep it out completely.

        Personally, I like my CD burner.

> > The kernel provides a nice clean interface to devices which conform to
> > the spec. Note that such raw access is, from what I can tell, part of
> > the spec, just the specific data sent using it isn't specified in the
> > spec and has been used by vendors to provide vendor-specific hooks,
> > which reminds me of 'SCSI generic'...
>
> It's dangerous - and the only legitimate use of this "feature" is one
> which shouldn't be done from within Linux in the first place.

        There are other uses of this direct access I suspect, perhaps not
as many under IDE as under SCSI, but they're there.

                Stephen

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