Is it at all possible for a user space non privileged process to
access some hardware in the system without making a system call or
otherwise going thru the kernel to gain access?

I have come across fleeting references to memory mapped I/O devices
where you can register some user space memory with the device and
after that I/O is done by just writing to this memory. I want to
understand if this is true or if the kernel is still involved in some
way under the hoods.

Any comments greatly appreciated!

Is it at all possible for a user space non privileged process to
access some hardware in the system without making a system call or
otherwise going thru the kernel to gain access?

I have come across fleeting references to memory mapped I/O devices
where you can register some user space memory with the device and
after that I/O is done by just writing to this memory. I want to
understand if this is true or if the kernel is still involved in some
way under the hoods.

Any comments greatly appreciated!

Mayuresh wrote:
Is it at all possible for a user space non privileged process to
access some hardware in the system without making a system call or
otherwise going thru the kernel to gain access?

I have come across fleeting references to memory mapped I/O devices
where you can register some user space memory with the device and
after that I/O is done by just writing to this memory. I want to
understand if this is true or if the kernel is still involved in some
way under the hoods.

Any comments greatly appreciated!

Take a look into the UIO (User I/O) kernel driver. It will provide you with
userland access to your hardware. You can also work with interrupts with
this driver in userland.

Or you can try this command line tool to access your hardware and/or use it
as an example how to do it:http://www.pengutronix.de/software/memedit/downloads/memedit-0.7.tar.gz

jbe

On Sep 24, 3:02 am, Juergen Beisert <jbeis... at (no spam) netscape.net> wrote:
Mayuresh wrote:
Is it at all possible for a user space non privileged process to
access some hardware in the system without making a system call or
otherwise going thru the kernel to gain access?

I have come across fleeting references to memory mapped I/O devices
where you can register some user space memory with the device and
after that I/O is done by just writing to this memory. I want to
understand if this is true or if the kernel is still involved in some
way under the hoods.

Any comments greatly appreciated!

Take a look into the UIO (User I/O) kernel driver. It will provide you
with userland access to your hardware. You can also work with interrupts
with this driver in userland.

Or you can try this command line tool to access your hardware and/or use
it as an example how to do it:
http://www.pengutronix.de/software/memedit/downloads/memedit-0.7.tar.gz


Not sure if you meant to point to something else - I downloaded the
above but see nothing relevant.

Hello,

Is it at all possible for a user space non privileged process to
access some hardware in the system without making a system call or
otherwise going thru the kernel to gain access?

I have come across fleeting references to memory mapped I/O devices
where you can register some user space memory with the device and
after that I/O is done by just writing to this memory. I want to
understand if this is true or if the kernel is still involved in some
way under the hoods.

Any comments greatly appreciated!

On Sep 24, 11:28 am, Mayuresh <b166er.... at (no spam) gmail.com> wrote:

Hello,

Is it at all possible for a user space non privileged process to
access some hardware in the system without making a system call or
otherwise going thru the kernel to gain access?

I have come across fleeting references to memory mapped I/O devices
where you can register some user space memory with the device and
after that I/O is done by just writing to this memory. I want to
understand if this is true or if the kernel is still involved in some
way under the hoods.

Any comments greatly appreciated!

Try this earlier post from comp.os.linux.embedded group ""Writing to a
device at a known physical address":

http://groups.google.com.au/groups/search?hl=en&qt_s=1&q=%22Writing+t...

Is it at all possible for a user space non privileged process to
access some hardware in the system without making a system call or
otherwise going thru the kernel to gain access?

I have come across fleeting references to memory mapped I/O devices
where you can register some user space memory with the device and
after that I/O is done by just writing to this memory. I want to
understand if this is true or if the kernel is still involved in some
way under the hoods.