I'm using the Cortex M3 MPU port and I'd like to configure my application to protect only the OS data, while allowing the non-privileged tasks access to everything else; however there doesn't seem to be a simple way to achieve this. The OS appears to be reserving MPU regions 0-3 for itself, and allowing regions 4-7 to be set per task. Since higher index MPU regions override lower ones, wouldn't it be better to do this the other way around (OS uses 4-7 and tasks use 0-3)? Is there another way to achieve the configuration I'm after?

Declare a static const MPU regions structure that covers all memory not used by the kernel, then assign that to each task as they are created.

Hi,

I just finish coding a simple application with the Cortex-M4 and What I did is changed the way the initial port was done.

probably a way of doing what you want, is to disable background, set region 0 (all the 4 gig) to USER_RW and then set region 7 to privileged RW for the OS section. If you want to protect also the flash section you will need to add the Region 6 to the flash section too.

This should work. With this setup, you should have 4 or 3 free region for your tasks.

Jonathan

Jonathan Le 2013-12-03 17:13, bainorama a écrit : > > I'm using the Cortex M3 MPU port and I'd like to configure my > application to protect only the OS data, while allowing the > non-privileged tasks access to everything else; however there doesn't > seem to be a simple way to achieve this. The OS appears to be > reserving MPU regions 0-3 for itself, and allowing regions 4-7 to be > set per task. Since higher index MPU regions override lower ones, > wouldn't it be better to do this the other way around (OS uses 4-7 and > tasks use 0-3)? Is there another way to achieve the configuration I'm > after? > > ------------------------------------------------------------------------ > > Cortex M3 Order of MPU regions > https://sourceforge.net/p/freertos/discussion/382005/thread/32662fa9/?limit=50#6529 > > ------------------------------------------------------------------------ > > Sent from sourceforge.net because you indicated interest in > https://sourceforge.net/p/freertos/discussion/382005/ > > To unsubscribe from further messages, please visit > https://sourceforge.net/auth/subscriptions/ > > > -- > This message has been scanned for viruses and > dangerous content by MailScanner http://www.mailscanner.info/, and is > believed to be clean.