Re: poll

[Ben Greear]

Richard B. Johnson wrote:
> On Thu, 17 Jun 2004, Ben Greear wrote:
>
>
> > Richard B. Johnson wrote:
> >
> > > Hello,
> > > Is it okay to use the 'extra' bits in the poll return value for
> > > something? In other words, is the kernel going to allow a user-space
> > > program to define some poll-bits that it waits for, these bits
> > > having been used in the driver?
> >
> > Can't you just do a read and determine from the results of the read
> > what you actually got?  If not, add framing to your message so that
> > you *CAN* determine one message type from another...
> >
> > Ben
>
>
> The mailbox read(s) is/are 32-bit int(s). There is no way to identify
> it as being "new" or something that was written two weeks ago.
> That's why we use poll. Poll says 'I got something new for you'.

Then use 3 different file descriptors to poll/read.  That seems more
efficient anyway as it doesn't wake the folks who don't care.

Ben

--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc  http://www.candelatech.com

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