Linux Driver Porting Information

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Which is better porting drivers from another OS or writing from scratch?

Porting
9
36%
Scratch
16
64%
 
Total votes: 25

0xCesar
Posts: 2
Joined: Tue Jun 12, 2007 11:15 pm
Location: Cracow

Post by 0xCesar » Sun Nov 25, 2007 9:54 pm

FlyingIsFun1217 wrote:From what I know, though, most linux drivers are coded using assembly.
Well, you are wrong. Linux drivers are written in C.

FlyingIsFun1217
Posts: 475
Joined: Sun Jun 10, 2007 3:56 am

Re: odd

Post by FlyingIsFun1217 » Sun Nov 25, 2007 10:00 pm

disks86 wrote:I don't see how that would be possible if they were assembly unless they ported the drivers each time.
Well, wouldn't they? Drivers aren't portable to my understanding.

I'll check out wikipedia, to make sure I'm not feeding everybody evil lies! :twisted:

FlyingIsFun1217 :)

FlyingIsFun1217
Posts: 475
Joined: Sun Jun 10, 2007 3:56 am

Post by FlyingIsFun1217 » Sun Nov 25, 2007 10:08 pm

Hey! Cool! I'm wrong!

I never realized:
In order to develop Linux device drivers, it is necessary to have an understanding of the following:

C programming. Some in-depth knowledge of C programming is needed, like pointer usage, bit manipulating functions, etc.

Microprocessor programming. It is necessary to know how microcomputers work internally: memory addressing, interrupts, etc. All of these concepts should be familiar to an assembler programmer.
(http://www.freesoftwaremagazine.com/art ... vers_linux)

So I guess what I was getting messed up on is that they can be coded in C, but use assembly ideas.

Nevermind, disregard me!
FlyingIsFun1217 :)

GreatLord
Developer
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Location: Sweden

Post by GreatLord » Sun Nov 25, 2007 10:49 pm

Windows and reactos provide all low level api u need.
and using asm in driver are against windows and reactos desgin.
it is total forbien. people please read how windows driver desgin before speak.

FlyingIsFun1217
Posts: 475
Joined: Sun Jun 10, 2007 3:56 am

Post by FlyingIsFun1217 » Mon Nov 26, 2007 3:18 am

GreatLord wrote:Windows and reactos provide all low level api u need.
and using asm in driver are against windows and reactos desgin.
it is total forbien. people please read how windows driver desgin before speak.
Greatlord, I meant translating. I was misunderstood that linux drivers were mostly coded in assembly (which they are not). To translate that, you would need to know assembly.

FlyingIsFun1217

Mna.
Posts: 122
Joined: Thu Dec 02, 2010 3:13 pm

Re: Linux Driver Porting Information

Post by Mna. » Thu Jan 06, 2011 5:32 am

So, I am wondering, Are there any guide of porting Linux driver to Reactos?
or at least from Linux to Windows?

Haos
Test Team
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Re: Linux Driver Porting Information

Post by Haos » Thu Jan 06, 2011 1:13 pm

I really doubt that, its more of crafting, artistic job, rather than something you coul tutorialize.

Mna.
Posts: 122
Joined: Thu Dec 02, 2010 3:13 pm

Re: Linux Driver Porting Information

Post by Mna. » Thu Jan 06, 2011 4:16 pm

The only thing somehow similar I found at the moment is:

A Comparison of the Linux and Windows Device Driver Architectures
http://osll.spb.ru/attachments/183/Linu ... arison.pdf

Mna.
Posts: 122
Joined: Thu Dec 02, 2010 3:13 pm

Re: Linux Driver Porting Information

Post by Mna. » Thu Jan 06, 2011 5:37 pm

Haos » 06 Jan 2011 11:13
I really doubt that, its more of crafting, artistic job, rather than something you could tutorialize.
I haven't yet dug it thoroughly, but does this type of job or driver porting really require intense research at every step?,
and couldn't this process made easy by outlining of important knowledge and eventually automated in some or other way?

***
Other paper I've found:
Comparing Windows XP and Linux. Windows Operating System Internals - by David A. Solomon and al.
http://fmgroup.polito.it/cabodi/dida/ps ... -linux.ppt

Interesting document about course of how USB appears in Linux: the similar way as people do for ROS, antisimmetric way, I would say:
"Reverse engineering Windows USB device drivers for the purpose of
creating compatible device drivers for Linux"

http://www.reactivated.net/weblog-conte ... se-0.2.txt

So Linux kernel developers reverse-engineered Windows USB drivers, and now ROS developers port Linux drivers "back" into ReactOS

Z98
Release Engineer
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Re: Linux Driver Porting Information

Post by Z98 » Thu Jan 06, 2011 6:51 pm

When it comes to drivers, a "port" is effectively a rewrite. The Linux devs reversing Windows USB drivers was to figure out the protocol such devices were using I believe, not so they could use any code in the drivers. And note that the need to reverse it by definition means there's not going to be much, if any, code sharing going on, since they did not have the source code to begin with. It would generally be easier to just look at a piece of hardware's specifications and write a driver from scratch. The only useful information a Linux driver could provide is if there's something missing in the spec that the Linux devs have discovered and they incorporated a workaround. But that workaround would still have to be rewritten against the Windows driver API. It is, conventionally, very difficult to port an already existing driver to another OS architecture. The only way to "share" significant amounts of code is to isolate all of the code that works on the device and the code that handles I/O through the OS from each other. But this must be done at the start of development. Trying to do it afterward is again, a rewrite.

hto
Developer
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Joined: Sun Oct 01, 2006 3:43 pm

Post by hto » Thu Jan 06, 2011 7:46 pm

I heard about some projects which aim to help with driver porting / reusing…

Mna.
Posts: 122
Joined: Thu Dec 02, 2010 3:13 pm

Re: Linux Driver Porting Information

Post by Mna. » Thu Jan 06, 2011 9:09 pm

Z98, thank you for reply.

Yes, in fact there are only few reasons to port drivers from somewhere:
  • 1. unknown hardware specification - then looking up to implementation we acquire necessary knowledge
  • 2. hard problems with hardware, f.ex. "quirks" type problems of Linux - or when several devices communicate each with other, making overall behavior difficult to debug
  • 3rd reason could be called "architectureal experience gaining" - learning on foreign implementation in particular OS, to avoid coincidence with the same problems in ROS.
So far, the first point is inevitable, since many devices have closed source device driver for Windows - and many of them are now get their OSS counterpart, and only way to reimplement it in ROS is to either "port" it, or "rewrite" it such or other way.

Mna.
Posts: 122
Joined: Thu Dec 02, 2010 3:13 pm

Re: Linux Driver Porting Information

Post by Mna. » Sun Jan 23, 2011 1:58 am

hto wrote:I heard about some projects which aim to help with driver porting / reusing…
Could you please remember some references or links on that?... It's just became interesting to me

hto
Developer
Posts: 2193
Joined: Sun Oct 01, 2006 3:43 pm

Post by hto » Sun Jan 23, 2011 4:21 am

> Could you please remember some references or links on that?

Some links to some driver-related projects were posted on this forum or on ros-dev ML. I do not remember details, will try to search…

Also, I remember talks about using Linux and BSD drivers in GNU Hurd on their mailing lists (using some glue project, which itself can be ported to different OSes). I don't know, can it be helpful here, or not.

Mna.
Posts: 122
Joined: Thu Dec 02, 2010 3:13 pm

Re: Linux Driver Porting Information

Post by Mna. » Fri Jun 10, 2011 5:24 pm

Interesting news
TheRegister: Intel teaches machines to build own device drivers /Game theory versus clumsy coders/
Intel Labs is working to automate the tedious and error-prone process of writing device drivers and porting them to different operating systems.

Explaining the need for a tool that could synthesize device drivers, Intel Labs software engineer Arun Raghunath told The Reg: "A bunch of studies have shown that the prime cause of crashes in operating systems are device drivers. They're notoriously hard to get right."
...
(Russian translation)

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