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Re: update on the device driver framework
From: |
Marcus Brinkmann |
Subject: |
Re: update on the device driver framework |
Date: |
Thu, 28 Aug 2003 14:06:51 +0200 |
User-agent: |
Mutt/1.5.4i |
On Tue, Aug 26, 2003 at 09:34:50PM +0200, Peter 'p2' De Schrijver wrote:
> Only threads which have registered as trusted are allowed to access
> device drivers. The checks is simple done by checking the senders
> id against a table of known threads.
There is a simple way to do it in O(1) anyway. Require the user to supply
the index in the table. So if a user sends a message foo (5, something),
then lookup entry 5 in the table (after performing a range check of course)
and check if the sender thread ID matches.
This way you don't have to worry about the number of threads being
registered. Only insertion can take a bit longer if you look for deleted
entries. But that should be ok.
> * Device Drivers
> ** Classes
> - character: This the standard tty as known in the Unix environment.
I am not sure you want full tty functionality, though. A minimal interface
that allows to implement the rest on top of it, as Wagi did for OSKit,
should be ok, I think.
But I am not sure what the purpose of these classes is.
> *** IRQ priorities
> All IRQs on L4 have priorities, so if an IRQ occurs any IRQ lower
> then the first IRQ will be blocked until the first IRQ has been
> acknowlegded. ISR priorities must much the hardware priority
> (danger of priority inversion). Furthermore the IRQ acknowledgment
> order is important.
"must much" -> "must match"
Thanks,
Marcus
--
`Rhubarb is no Egyptian god.' GNU http://www.gnu.org address@hidden
Marcus Brinkmann The Hurd http://www.gnu.org/software/hurd/
address@hidden
http://www.marcus-brinkmann.de/