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Raspberry Pi 2 JTAG error on memory access

Alessandro

Hi all,

I am trying to connect to the RPi2 JTAG.

I have the following setup

- Raspberry Pi 2 running Raspbian 8.0 (Jessie)

- OpenOCD 0.9.0 with a J-Link EDU connected to a Ubuntu system.

I setup the GPIO in order to expose the JTAG interface and the JTAG connection works: I can halt/resume processors.

The issues start whenever I tried to access the memory (with the CPU halted).

For example

> halt                                
ttbcr 0ttbr0 378a806attbr1 406a
rpi2.cpu.3 rev 5, partnum c07, arch f, variant 0, implementor 41
number of cache level 2
cache l2 present :not supported
rpi2.cpu.3 cluster f core 3 multi core
target state: halted
target halted in ARM state due to debug-request, current mode: Supervisor
cpsr: 0x60000093 pc: 0x80021868
MMU: enabled, D-Cache: enabled, I-Cache: enabled

> dump_image ram.bin 0x08000 0x1000
timeout waiting for DSCR bit change
in procedure 'cache_config'

Is there anyone aware of this issue?

Is there anything I can do to dig into the problem? I was thinking about disabling the cache...

Any help would be appreciated.

Best

Alex

  • +1

    Could it be related to some cache coherence issue?

    I was able to access the memory via JTAG by using a bare metal firmware on the Raspberry (no OS) which does nothing but configure the JTAG on the GPIO.

    Here the only notable difference is that the 1st level cache and MMU are disabled.

    Thanks for any hint.