Re: Direct access to hardware

From: James Sutherland (jas88@cam.ac.uk)
Date: Tue Jul 25 2000 - 09:50:22 EST


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.
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.

> This keeps the vendor specific *junk* out of the kernel and in
> userland.

I'd rather keep it out completely.

> 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.

James.

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