Re: [Qemu-devel] [PATCH] target-arm: Implement DBGDTRRX_EL0/DBGDTRTX_EL0 MSR

[Peter Maydell]

On 9 February 2016 at 20:59, Dirk Müller <address@hidden> wrote:
> This is used by the ARM JTAG DCC console in the Linux kernel,
> but can be ignored in order to continue booting.
>
> Co-Authored-By: Andreas Schwab <address@hidden>
> Signed-off-by: Dirk Mueller <address@hidden>
> ---
>  target-arm/helper.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index 954e6e8..abce416 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -3704,6 +3704,9 @@ static const ARMCPRegInfo debug_cp_reginfo[] = {
>      { .name = "DBGVCR",
>        .cp = 14, .opc1 = 0, .crn = 0, .crm = 7, .opc2 = 0,
>        .access = PL1_RW, .type = ARM_CP_NOP },
> +    { .name = "DBGDTRxX_EL0", .state = ARM_CP_STATE_BOTH,
> +      .cp = 14, .opc0 = 2, .opc1 = 3, .crn = 0, .crm = 5, .opc2 = 0,

You've marked the register as STATE_BOTH, but this is the wrong
encoding for the AArch32 version (which has opc1 = 0); you'll
need to split into one regdef for each.

> +      .access = PL0_RW, .type = ARM_CP_NOP },
>      REGINFO_SENTINEL
>  };

Can you also add an access function for this register, please?
https://git.linaro.org/people/peter.maydell/qemu-arm.git target-arm.next
has the patches I sent recently that implement the MDCR_EL*.TDA
traps, and this new register is in the same category.
Minimum requirement: use access_tda() and add a comment that
we don't implement the configurable EL0 traps. (this is what
we do for MDCCSR_EL0 at the moment). Optional extra: implement
a new access_tdcc() which checks for the MDSCR_EL1.TDCC trap
and the MDCR_EL2.TDA and MDCR_EL3.TDA traps, and use that.
(Bonus points: then use that access function on the other
couple of registers which need it.)

thanks
-- PMM