#10891 BLOC Future : OFW XO-1.75 - lockdown SPI FLASH writes

[Zarro Boogs per Child]

#10891: OFW XO-1.75 - lockdown SPI FLASH writes
-----------------------------------------+----------------------------------
           Reporter:  wmb at firmworks.com  |       Owner:  wad           
               Type:  task               |      Status:  new           
           Priority:  blocker            |   Milestone:  Future Release
          Component:  hardware           |     Version:  1.75-A3       
         Resolution:                     |    Keywords:                
        Next_action:  design             |    Verified:  0             
Deployment_affected:                     |   Blockedby:                
           Blocking:                     |  
-----------------------------------------+----------------------------------
Changes (by wmb at firmworks.com):

  * owner:  wmb at firmworks.com => wad
  * priority:  normal => blocker
  * version:  1.75-A2 => 1.75-A3
  * component:  ofw - open firmware => hardware
  * milestone:  1.75-firmware => Future Release


Comment:

 I think it's not possible to use the MMP2 security features to prevent
 writes to the SPI boot flash.  While one can set the SSP1 module to secure
 mode, thus preventing access to it from the P4J core, I don't see any way
 to prevent the OS from using the MFPR registers to map GPIOs to those
 pins, thus enabling writes via a bit-banging driver.

 I think we need to reinstate a hardware lockout flip-flop.

-- 
Ticket URL: <http://dev.laptop.org/ticket/10891#comment:2>
One Laptop Per Child <http://laptop.org/>
OLPC bug tracking system