03-17-2011
Quote:
Originally Posted by
Chrisdot
Well, Corona688 I see you have very large knowledge about writing linux drivers
I've done enough work with them to know they are a severe challenge. I've occasionally had to alter some predefined values. I wrote a linux driver that prints 'hello world' to dmesg. I couldn't write a real driver yet.
But I know enough to tell you that
windmills device drivers don't work that way. The kernel isn't going to reach into userspace, rip one function out of your userspace program, and run it raw because you don't get the same kind of stack; you don't get an ordinary heap; you don't get
anything from libc; you don't get the same kind of files -- what does stderr even
mean when you have no descriptor table? -- you don't get easy system calls like read() and write(); you don't even get easy, direct access to large amounts of available memory, and what memory there is is laid out in an alien way. The ease of all these things in userspace is a convincing illusion created by the kernel, more or less, and the way to use them is to be in userspace. Ordinary code can't run in kernel space any more than you could breathe in a vacuum.
Nearly all communication with the kernel is done through files and system calls instead. Your device driver can create a device file under /dev/ tied to your own kernel functions. someone opens it and your driver's read handler gets called, someone reads it and your device's read-handler gets called, etc. On boot, something in userspace could read from the ROM device and dump it into your special firmware-loading device file, and you'd be done.
Last edited by Corona688; 03-17-2011 at 01:15 PM..
This User Gave Thanks to Corona688 For This Post:
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
I just set up an ftp server with Red Hat 5.2. I am doing the work, I'm baby stepping, but it seems like every step I get stuck. Currently, I'm trying to set up a crontab job, but I'm getting the following message: /bin/sh: /usr/bin/vi: No such file or directory. I see that vi exists in /bin/vi,... (3 Replies)
Discussion started by: kwalter
3 Replies
2. Programming
Hi-
I need the cpp call that will tell me the full path to the app I'm running in. For example, I'm running in a loaded library for either mozilla or firefox, but would like to know the full path to the executable
/usr/bin/firefox
/usr/bin/mozilla
/usr/local/firefox1_5
etc...
(For... (4 Replies)
Discussion started by: erwinfletch
4 Replies
3. Linux
Hi all,
I am working on USB data monitoring on Fedora Core 9. Kernel 2.6.25 has a built-in module (the one that isn't loadable, but compiles and links statically with the kernel during compilation) to snoop USB data. It is in <kernel_source_code>/drivers/usb/mon/.
I need to know if I can... (0 Replies)
Discussion started by: anitemp
0 Replies
4. Shell Programming and Scripting
Okay, so I have two "Hello, world!" scripts, "test.pl" and "test.sh".
#!/bin/perl -w
use strict;
print "Hello, world!\n";
#!/bin/csh
echo Hello,\ world!
When I run test.pl, it runs instantly, always. When I run test.sh, it takes anywhere between 4 and 22 seconds!
I'd like to know what... (3 Replies)
Discussion started by: acheong87
3 Replies
5. UNIX for Dummies Questions & Answers
Hi,
I have a problem I don't understand with fuser.
I launch a simple shell script mysleep.sh:
I launch the command fuser -fu mysleep.sh but fuser doesn't return anything excepted:
mysleep:
Then I modify my script switching from #!/bin/sh to #!/bin/ksh
I launch the command fuser -fu... (4 Replies)
Discussion started by: Peuj
4 Replies
6. OS X (Apple)
Q1. I understand that /usr/local/bin means I can install/uninstall stuff in here and have any chance of messing up my original system files or effecting any other users. I created this directory myself.
But what about the directory I didn't create, namely /Users/m/bin? How is that directory... (1 Reply)
Discussion started by: michellepace
1 Replies
7. Programming
I have made an packet capture application running on intel machine, it is capturing packets with src address- 17.0.0.0 destination ip- 66.0.0.0, source port- 0, destination port- 0, and protocol- 0 what does these packets mean ?
The code written to interpreter captured bytes is given below.... (5 Replies)
Discussion started by: arunpushkar
5 Replies
8. Ubuntu
Is there any way to compile smbfs module in kernel 3.10 running Ubuntu 12.04 LTS. I did a 'make menuconfig' and it shows cifs. I found out online that smbfs is deprecated and replaced by cifs. I have an old system with kernel version 2.4 which only has smbfs (no cifs). Is it possible to compile... (1 Reply)
Discussion started by: Monil
1 Replies
9. AIX
Hi,
I am planning to install a version of Informatica on my AIX box. It requires a specific java build in pap6470_27sr2-20141101_01(SR2).
The current link for IBM 64-bit SDK for AIX®, JavaTM Technology Edition, Version 7 Release 1 has a more recent version in j7r164redist.7.1.0.75.bin.
Is... (4 Replies)
Discussion started by: meetpraveens
4 Replies
10. Shell Programming and Scripting
Some question about the usage of shell scripts:
1.) Are the commands of the base shell scripts a subset of bash commands?
2.) Assume I got a long, long script WITHOUT the first line.
How can I find out if the script was originally designed für "sh" or "bash"?
3.) How can I check a given... (3 Replies)
Discussion started by: pstein
3 Replies
LEARN ABOUT MOJAVE
task::weaken
Task::Weaken(3) User Contributed Perl Documentation Task::Weaken(3)
NAME
Task::Weaken - Ensure that a platform has weaken support
DESCRIPTION
One recurring problem in modules that use Scalar::Util's "weaken" function is that it is not present in the pure-perl variant.
While this isn't necesarily always a problem in a straight CPAN-based Perl environment, some operating system distributions only include
the pure-Perl versions, don't include the XS version, and so weaken is then "missing" from the platform, despite passing a dependency on
Scalar::Util successfully.
Most notably this is RedHat Linux at time of writing, but other come and go and do the same thing, hence "recurring problem".
The normal solution is to manually write tests in each distribution to ensure that "weaken" is available.
This restores the functionality testing to a dependency you do once in your Makefile.PL, rather than something you have to write extra
tests for each time you write a module.
It should also help make the package auto-generators for the various operating systems play more nicely, because it introduces a dependency
that they have to have a proper weaken in order to work.
How this Task works
Part of the problem seems to stem from the fact that some distributions continue to include modules even if they fail some of their tests.
To get around that for this module, it will do a few dirty tricks.
If Scalar::Util is not available at all, it will issue a normal dependency on the module. However, if Scalar::Util is relatively new ( it
is >= 1.19 ) and the module does not have weaken, the install will bail out altogether with a long error encouraging the user to seek
support from their vendor (this problem happens most often in vendor-packaged Perl versions).
This distribution also contains tests to ensure that weaken is available using more normal methods.
So if your module uses "weaken", you can just add the following to your Module::Install-based Makefile.PL (or equivalent).
requires 'Task::Weaken' => 0;
SUPPORT
Bugs should be always be reported via the CPAN bug tracker at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Task-Weaken>
For other issues,contact the author.
AUTHOR
Adam Kennedy <adamk@cpan.org>
SEE ALSO
Task, Scalar::Util, <http://ali.as/>
COPYRIGHT
Copyright 2006 - 2011 Adam Kennedy.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
The full text of the license can be found in the LICENSE file included with this module.
perl v5.18.2 2011-03-08 Task::Weaken(3)