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From: Alan McKinnon <alan.mckinnon@gmail.com>
To: gentoo-user@lists.gentoo.org
Subject: Re: [gentoo-user]  Re: New xorg.conf with x11-base/xorg-server-1.5.3-r5
Date: Sun, 17 May 2009 11:19:49 +0200	[thread overview]
Message-ID: <200905171119.49998.alan.mckinnon@gmail.com> (raw)
In-Reply-To: <4A0F6962.2020006@coolmail.se>

On Sunday 17 May 2009 03:33:22 pk wrote:
> Alan McKinnon wrote:
> > As I see it, at the bottom of the stack you have a kernel and at the top
> > a user space app (the X server will do for an example). Plug in a USB
> > device that the app can use, and the kernel needs to make a node in /dev
> > for it if it's not already there. The kernel should not be interrogating
> > the device for all possible info - that is expensive - and doesn't need
> > to. It only needs enough info to know what driver, major and minor
> > numbers to use. X OTOH, can
>
> I couldn't agree more. And this is what Udev, as a user space app, does.
> The only thing it doesn't handle is communicating with other user space
> apps; this is currently Hals job.
>
> > the current model uses udev as the interface to the kernel's nodes and
> > HAL as the interface to exactly what hardware you have. Seems pretty sane
> > for the most usual use case. At some point in the stack you will need the
> > OS-dependant part, my guess is the best place is between hal and udev.
> > Only Linux uses
>
> Well, as I understand it this is what it looks like today:
>
> kernel <-> udev (or equivalent for non-linux kernel/OS) <-> hal <-> dbus
> <-> user apps
>
> To me that seems a bit redundant...

No, there's nothing redundant in that. udev talks kernel-speak, hal talks 
userspace-speak. Hal could be distro-agnostic, udev can't be (not in a sane 
environment) and dbus is simply a transport layer for messages. That's five 
different functions going on, and none of them logically belong with any other 
in the same layer.

> What I would like to see:
>
> kernel <-> udev <-> user apps

Then X must talk to udev directly. Two problems:

- only Linux has udev. Other OSes may not need, want or be willing to touch 
udev with a bargepole.
- X is multi-platform. Good luck getting Keith to agree to make it essentially 
Linux only :-)

> Or at the most:
>
> kernel <-> udev <-> daemon <-> user apps.

But you have that in the current setup. Hal (for better or worse) is the 
daemon. dbus is simply a message transport and can be omitted from the 
conceptual diagram

> > udev, but all OSes use something in that spot. And if not, they have
> > static nodes.
>
> Yes, but if the developers could agree on a common API for the udev
> daemon and it's equivalents on other platforms (what does BSD use?)...
> Or if they could agree on using "Hal v2" (rewritten from scratch with no
> or a minimum of dependencies).

I don't think that's feasible. Easiest would be the bottom layer of hal has 
OS-specific code to talk to udev (or it's equivalent in other OSes). Or 
perhaps a plugin/module type system. 

> > Meanwhile we have an acknowledged problem with hal - it's too complex,
> > too many things have been shoved into it that were never catered for in
> > the design, configuration is horrific - and the devs are having their
> > usual spirited debate about how best to approach a solution. This is
> > perfectly normal and perfectly healthy
>
> Yes, I guess so. Since I'm (currently) not in the position to help out
> I'll have to live with whatever they come up with. But sometimes it's a
> bit frustrating... Sorry for the ranting.

Hey, it could be worse.

You could be forced to use Windows...


-- 
alan dot mckinnon at gmail dot com



  reply	other threads:[~2009-05-17  9:21 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-07  8:39 [gentoo-user] New xorg.conf with x11-base/xorg-server-1.5.3-r5 Mick
2009-04-07  8:46 ` Volker Armin Hemmann
2009-04-07 10:26   ` Mick
2009-04-07 10:46     ` Volker Armin Hemmann
2009-04-07 11:02       ` [gentoo-user] " Nikos Chantziaras
2009-04-07 11:17         ` Alan McKinnon
2009-04-07 11:25           ` Volker Armin Hemmann
2009-04-08 15:01             ` 7v5w7go9ub0o
2009-05-15 15:55             ` Tony Davison
2009-05-16 16:33               ` Mick
2009-04-07 13:08       ` [gentoo-user] " Dale
2009-04-07 10:53   ` Peter Humphrey
2009-04-07  9:19 ` Alan McKinnon
2009-04-07 10:34   ` Mick
2009-04-07 10:21 ` Khanh Nguyen
2009-04-07 14:14   ` sean
2009-04-07 14:51     ` Paul Hartman
2009-04-07 15:22       ` Volker Armin Hemmann
2009-04-07 15:50         ` Paul Hartman
2009-04-07 16:31           ` Volker Armin Hemmann
2009-04-07 18:12             ` [gentoo-user] " ABCD
2009-04-08 15:45             ` [gentoo-user] " Paul Hartman
2009-04-08 16:12               ` Volker Armin Hemmann
2009-04-08 16:18                 ` Paul Hartman
2009-05-15 16:03                   ` Volker Armin Hemmann
2009-05-15 16:10                     ` Alan McKinnon
2009-05-15 16:41                       ` Dale
2009-05-15 16:59                         ` Paul Hartman
2009-05-15 17:26                           ` Volker Armin Hemmann
2009-05-15 17:42                           ` Dale
2009-05-15 16:42                       ` Dale
2009-05-15 16:57                         ` Alan McKinnon
2009-05-15 17:45                           ` Dale
2009-05-15 20:05                           ` pk
2009-05-15 20:24                             ` Volker Armin Hemmann
2009-05-15 20:38                               ` Aaron Clark
2009-05-15 20:39                               ` Mark Knecht
2009-05-15 20:38                             ` [gentoo-user] " Nikos Chantziaras
2009-05-15 20:44                               ` Alan McKinnon
2009-05-15 20:51                                 ` Nikos Chantziaras
2009-05-15 20:54                                   ` Alan McKinnon
2009-05-16 17:14                                     ` pk
2009-05-16 17:55                                       ` Alan McKinnon
2009-05-16 18:10                                         ` Dale
2009-05-17 17:10                                           ` bn
2009-05-17 18:00                                             ` Alan McKinnon
2009-05-17 18:16                                               ` Mark Knecht
2009-05-17 19:12                                                 ` Dale
2009-05-17 19:22                                                   ` Mark Knecht
2009-05-17 21:20                                                     ` Dale
2009-05-18  4:07                                                     ` was [gentoo-user] Re: New xorg.conf with x11-base/xorg-server-1.5.3-r5 now old nvidia drivers Adam Carter
2009-05-18  4:22                                                       ` Dale
2009-05-18  5:00                                                         ` Adam Carter
2009-05-17 18:21                                               ` [gentoo-user] Re: New xorg.conf with x11-base/xorg-server-1.5.3-r5 bn
2009-05-17 19:02                                             ` Dale
2009-05-17  1:33                                         ` pk
2009-05-17  9:19                                           ` Alan McKinnon [this message]
2009-05-17 12:15                                             ` pk
2009-05-17 14:32                                               ` Alan McKinnon
2009-05-17 21:47                                             ` Volker Armin Hemmann
2009-04-07 15:52         ` [gentoo-user] " Joseph
2009-04-07 16:16           ` Neil Bothwick
2009-04-07 16:17           ` [gentoo-user] " Nikos Chantziaras
2009-04-07 23:13           ` [gentoo-user] " sean
2009-04-08 18:16             ` pk
2009-04-07 16:14         ` [gentoo-user] " Nikos Chantziaras
2009-04-07 16:45         ` [gentoo-user] " Mick
2009-04-07 17:02           ` Volker Armin Hemmann
2009-04-07 17:21             ` Mick
2009-04-07 20:27             ` sean
2009-04-07 20:32               ` Volker Armin Hemmann
2009-04-07 17:05           ` Sebastian Günther
2009-04-07 17:17             ` Mick
2009-04-07 20:37           ` Daniel Barkalow
2009-04-08  5:47             ` Mick

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