[RFC PATCH] clocksource: arm_arch_timer: disable the evtstrm via the cmdline

On Mon, Jun 20, 2016 at 02:30:02PM +0100, Will Deacon wrote:

On Mon, Jun 20, 2016 at 02:59:11PM +0200, Daniel Lezcano wrote:

quoted

On 06/20/2016 10:21 AM, Will Deacon wrote:

quoted

On Sun, Jun 19, 2016 at 10:08:38PM +0200, Daniel Lezcano wrote:

quoted

On 06/17/2016 03:43 PM, Will Deacon wrote:

[ Cc'ed tglx ]

quoted

Disabling the eventstream can be useful for debugging and development
purposes

If it is for debugging and development, why upstream this change ?

Mainly because it's desirable to be able to debug systems remotely, on
machines that you don't have direct access to and where recompiling the
kernel isn't necessarily an option. There are plenty of "no*" kernel
parameters already that fall into a similar category.

if the kernel is in development and debug, why this option can't be part of
debugging code ?

If recompiling isn't an option, how this can be for "debugging and
development" ?

Sorry, I wasn't very clear. The sort of use-case I'm envisaging is where
somebody is running a distro kernel on non-public hardware and sends me an
email about spinlock performance. Being able to disable the event stream
easily is a powerful tool in the small box of remote debugging tools and
would be useful in pinning down things like missing events.

So when I say "development and debug" I'm really thinking about *remote*
debug via a user, and then potentially the subsequent development of a
patch.

We should probably place this rationale in the commit message. e.g.
(fake emphasis):

Disabling the eventstream can be useful for *remotely* debugging *a
deployed production system*.

Mark.