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Subject: Re: PPs running in supervisor mode

Re: PPs running in supervisor mode

From: Antonius Hellmann <antonius.hellmann_at_gmx.de>
Date: Wed, 9 May 2007 18:18:26 +0200

Yes, this is correct: "In User mode, the control bits of the CPSR are protected from change, so only the condition code flags of the CPSR can be changed. In other (privileged) modes the entire CPSR can be changed." If the supervisor mode is the reason for the troubles, then I think it is worth, to modify the software.
  ----- Original Message -----
  From: Michael Sevakis
  To: Rockbox development
  Sent: Wednesday, May 09, 2007 5:40 PM
  Subject: Re: PPs running in supervisor mode

  Wouldn't software interrupts be needed to call code to switch to a supervisor mode when needed? I _am_ rather new to ARM and such but it's my educated guess atm based on our other big CPU. I fear major complication from it.
    ----- Original Message -----
    From: Antonius Hellmann
    To: Rockbox development
    Sent: Wednesday, May 09, 2007 2:03 AM
    Subject: PPs running in supervisor mode

    One idea, why we have these troubles with interrupt handling on the PP devices is, that probably the supervisor mode has some issues with interrupt switching? I understand, that the supervisor mode makes it easy to do register manipulations. But it might be more safe to run the rockbox application code in user mode.
Received on 2007-05-09


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