qemu_cortex_m3: enable MPU

[zephyrbot]

Reported by Andrew Boie:

We have a new SDK coming very soon with QEMU 2.10 final in it. This new QEMU appears to support the MPU in M profile CPUs.

Needless to say, being able to work with the ARM MPU in emulation would be a great asset in developing memory protection and also assuring that sanitycheck can find regressions for CI.

The new SDK should be released soon, Anas can provide binaries in the interim.

(Imported from Jira ZEP-2586)

[agross-oss]

There appears to be an issue with the emulation not doing the right thing w.r.t. the region. I contacted the qemu guys and I am working with them to resolve this.

[andrewboie]

I've asked @AdithyaBaglody to spend some time on this.
@agross-linaro any further details and engagement from QEMU team?
I see there has been some commits in this area for QEMU 2.11.

[lpereira]

Where do we stand on this, with regards to testing on Qemu?

[AdithyaBaglody]

hi so few updates on this. The small gist is as follows.
So as of now it is decided that we can get as much code merged as we can without breaking anything.(#7035)
Then we move to the new qemu version. Once that is done another PR #7399 which is already up can be merged once the CI and SDK are up.
On the blocking front there is still a test case failure I am debugging. But this issue is a MPU related and will come into picture when we are trying to merge #7399.

[AdithyaBaglody]

MPU enabled on mps2_an385 which should run on the latest qemu.
Hence closing this issue.