topic Re: SMPU and Debug Storage Buffer behaviour in MPC5xxx

SMPU and Debug Storage Buffer behaviour

avinashsharma — Tue, 10 May 2016 11:03:40 GMT

In case of SMPU is enabled along with HDBCR0[DSB] = Enabled.

e.g.

MPU RGD : 0x40000000 - 0x40000020 : Only Supervisor access is granted

1. In User Mode

2. SWC in user mode tries to write "0x0x40000000 ".

3. Write instruction stored in storage buffer.

4. CPU goes in "Supervisor Mode".

5. Storage Buffer instruction executes.

Question: Do we get a MPU exception at Point '5'?

Re: SMPU and Debug Storage Buffer behaviour

lukaszadrapa — Wed, 11 May 2016 07:51:36 GMT

Hi,

each store buffer entry contains 32-bits of data, 32-bits of address, size information and access attribute information in order to properly drive the attribute output signals on a buffered store access.

Supervisor/user access attribute is included too, so the answer is yes, exception will be triggered in described scenario.

Regards,

Lukas