Hi Stephen,
On Thu, Sep 20, 2012 at 05:57:40PM +0100, Stephen Boyd wrote:
> The reset value of the BCR, BVR, WCR, and WVR registers are all
> UNKNOWN on ARMv7. Unfortunately, reset_ctrl_regs() clears these
> registers *after* enabling monitor mode, not before, and so some
> implementations may experience UNPREDICTABLE behavior if the
> reset values of these registers are non-zero. Clear the
> breakpoints before enabling monitor mode so that we don't
> experience boot hangs/loops due to breakpoints being enabled
> out of reset.
>
> Signed-off-by: Stephen Boyd <sb...@codeaurora.org>
Aha, thanks for the patch. We should definitely zero these registers before
enabling monitor mode. However...
> +/* Determine if halting mode is enabled */
> +static int halting_mode_enabled(void)
> +{
> + u32 dscr;
> +
> + ARM_DBG_READ(c1, 0, dscr);
> +
> + if (WARN_ONCE(dscr & ARM_DSCR_HDBGEN,
> + "halting debug mode enabled. Unable to access hardware
> resources.\n")) {
> + return -EPERM;
> + }
> + return 0;
> +}
...it looks like debug arch 7.1 defines this bit as UNKNOWN when the OS lock
is clear, so we probably shouldn't be reading it at all. I'll pour myself a
stiff drink and start reading the debug arch docs to work out what on Earth
we should do.
Stay tuned.
Will
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
