Re: Should raw I/O be added to the kernel?

Chris Evans (chris@ferret.lmh.ox.ac.uk)
Fri, 18 Dec 1998 18:50:05 +0000 (GMT)


On Wed, 16 Dec 1998, Glendon Gross wrote:

> I am reminded of the catch-22 that results from loading products like
> Direct-X to a M$ environment. Enabling direct access to hardware often
> results in instability and system crashes, which anyone who loads the
> above product on a Windows 9x box can testify to after a program in
> userspace brings the whole system down, ad infinitum ad nauseum.

Raw IO isn't direct access to hardware, it's direct access to the hardware
_driver_. A user program with permission to access a raw device won't be
able to cause system instability any more than a user program with
permission to access a file. Indeed, the file access case has many more
layers of code to go through.

The classic example of allowing userspace direct access to hardware is X -
another lovely can of worms.

Chris

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