Re: access memory mapped registers

In message [off-list ref] you wrote:

why would it be better to use the device driver than via the mmap from user
space?

Reliability, robustnes, clean design, ...

Why do we have a separation into kernel and user space at all?

one of my criteria was to make sure no software mistake will cause the
kernel to hang, as
in the case of vxWorks we are running.  So, if I implement my access to the

Then don't weaken the memory protection of the Unix design.

device
in the device driver, doesn't that means if there are problem with the
device driver
portion, i will cause the kernel to hang?  Furthermore, any enhancement to

Don't you think that an application process that  will  write  random
data to your hardware will have a much higher potential to cause harm
than  a  carefully designed, implementred, reviewed and tested device
driver?

driver will require me to reinstall the kernel?  whereas if all my user
space
application handles the access to those devices, I can stop the user space
application,
update it with the new application without requiring the system to reboot?

You can dynamically load and unload device drivers.


Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
"Wish not to seem, but to be, the best."                  - Aeschylus

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