I’ve searched the Newsgroups and Knowledge Base and Tips but have not found
any info.
My question:
Is it possible to have a background task that non-destructively performs a
test of ALL RAM? I am refering to run-time conutinues operation. This would
be for a high risk medical device where it appears that our HW platform does
not support ECC RAM.
Any help/comments are appreciated.
Ed Theobald
Revis & Associates
Ed Theobald <edtheobald@starband.net> wrote:
Is it possible to have a background task that non-destructively performs a
test of ALL RAM? I am refering to run-time conutinues operation. This would
be for a high risk medical device where it appears that our HW platform does
not support ECC RAM.
I guess it would depend on the kind of “test” you want to preform. I’m not sure
what is meant by “non-destructively”. Testing RAM means, a read/write test - which
implies that you must destroy what was previously there, and verifiy that the new
information is stored, stable and can be read back. If you mean “transparently”
check the RAM while other processes run - without interruption then that gets
tricky. I would think it’s possible if you has an OS that could copy sections
of RAM, then fiddles the page tables so the virtual address map to the new RAM
section. Then lock out the section of RAM so it can’t be mapped while doing the
check. There could be problems, when certain software relies on physical mem
addresses (drivers etc) and the new RAM block becoming stale before the OS
could twiddle the page tables.
In the end, I believe it could be possible but I would seriously doubt you’d
get any kind of determinism out of the machine.
-Adam
amallory@qnx.com
Ram test are commonly done in a lot of mission critical systems that require
deterministic behavior. Our customers require both. We don’t use an RTOS
on any deliverables because of red tape, but I would expect validating ram
to be something of a concern to a large number of potential QNX clients.
This is not something to blow off saying it is impractical.
Pete Eddy