Re: [ANNOUNCE] FUSD v1.00: Framework for User-Space Devices

From: Eric W. Biederman (
Date: Sat Oct 13 2001 - 16:57:32 EST

"Pavel Machek" <> writes:

> Hi!
> > > Yep. And linmodem driver does signal processing, so it is big and
> > > ugly. And up till now, it had to be in kernel. With your patches, such
> > > drivers could be userspace (where they belong!). Of course, it would be
> > > very good if your interface did not change...
> >
> > I don't see how linmodem drivers apply. At least not at the low-level
> > because you actually have to driver the hardware, respond to interrupts
> > etc. On some of this I can see a driver split like there is for the video
> You don't actually need interrupts -- you *know* when next sample arrives.
> And port io is completely fine with iopl() ;-).

But DMA? You are talking about what amounts to a sound card driver.
And since in the cases that burn cpu time you have to process raw
sound samples into modem data, you need to shift a fair amount of
data. inb and outb just don't have the bandwidth. So you need a
kernel side component that drives the hardware to some extent.

Additionally you still don't need a FUSD driver for that case. All
you need is to have is a ptty. Because that is what modem drivers
are now. And the ptty route has binary and source compatiblity
to multiple unix platforms.

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This archive was generated by hypermail 2b29 : Mon Oct 15 2001 - 21:00:51 EST