[RFC v2 PATCH 1/1] ARM64: KGDB: Add FP/SIMD debug support

From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC v2 PATCH 1/1] ARM64: KGDB: Add FP/SIMD debug support
Date: Fri, 28 Feb 2014 17:36:36 +0000	[thread overview]
Message-ID: <20140228173636.GG30996@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <CALicx6v12DWQSqpP=pa_gJmyOqm4LmFHWc_9=n8Rt7M=krB+dQ@mail.gmail.com>

On Fri, Feb 28, 2014 at 11:08:58AM +0000, Vijay Kilari wrote:
> On Fri, Nov 29, 2013 at 3:27 PM, Vijay Kilari <vijay.kilari@gmail.com> wrote:
> >>> KGDB, being kernel debugger it was thought that allow
> >>> debugging only if kernel mode is supported.
> >>> In fact, I proposed (previous email)  to remove this condition and
> >>> allow to reading neon
> >>> registers always and allow write only if neon is in kernel mode.
> >>>
> >>
> >> I think KGDB is a special case here and should not considered as a
> >> user of kernel mode NEON. So even writing the registers should
> >> allowable regardless of this setting imo.
> >>
> 
>  Can we avoid checking on NEON state and allow debugger to
> access NEON registers irrespective of state to keep it simple?
> and just compile config is enough?

I'm afraid I don't follow... I think we *do* need to do the relevant
flush/sync operations, I just don't think it should be predicated on
KERNEL_MODE_NEON.

Will