On Thu, Sep 06, 2012 at 09:25:12AM +0100, Jon Medhurst (Tixy) wrote: > On Thu, 2012-09-06 at 11:50 +0800, Guodong Xu wrote: > > > <guodong> I think there are two ways to access CCI from non-secure mode: > > 1. In Hyp mode, issue an SMC instruction to enter Secure Monitor mode and > > do the job. > > 2. In secure mode (early stage in boot.S, or in monitor.S), change 'Secure Access Register' of CCI-400 > > to enable non-secure access. But this compromises system's security. I tested this and it can work: > > I notice that the Linux cpu_idle code we have for TC2 contains functions > which manipulates the CCI, so I think it would be good if we enabled > non-secure access to it, otherwise I think we will have problems > somewhere down the line. I think the bootwrapper should do all its work in the Secure World for now anyway (assuming my patches work). At the very least, we would need this so that the bootwrapper can program the CCI Secure Access Register conditionally depending on the board type and configuration. So, the bootwrapper would do this: 1) examine semihosting command-line and/or DT 2) configure CCI snoops and Non-Secure access, if needed 3) switch to NS Hyp mode and boot Linux If my patches for delaying the switch to Hyp mode work, then it should be possible to add (1) and (2) on top of that. Cheers ---Dave _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
