On Thu, May 24, 2018 at 12:50:18PM -0500, Rob Herring wrote: > Deferring probe can wait forever on dependencies that may never appear > for a variety of reasons. This can be difficult to debug especially if > the console has dependencies or userspace fails to boot to a shell. Add > a timeout to retry probing without possibly optional dependencies and to > dump out the deferred probe pending list after retrying. > > This mechanism is intended for debug purposes. It won't work for the > console which needs to be enabled before userspace starts. However, if > the console's dependencies are resolved, then the kernel log will be > printed (as opposed to no output). > > Signed-off-by: Rob Herring <[email protected]> > --- > .../admin-guide/kernel-parameters.txt | 7 +++++ > drivers/base/dd.c | 28 ++++++++++++++++++- > 2 files changed, 34 insertions(+), 1 deletion(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt > b/Documentation/admin-guide/kernel-parameters.txt > index 11fc28ecdb6d..dd3f40b34a24 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -809,6 +809,13 @@ > Defaults to the default architecture's huge page size > if not specified. > > + deferred_probe_timeout= > + [KNL] Set a timeout in seconds for deferred probe to > + give up waiting on dependencies to probe. Only specific > + dependencies (subsystems or drivers) that have opted in > + will be ignored. This option also dumps out devices > + still on the deferred probe list after retrying.
Doesn't sound like a debugging-only option. I can see devices enabling this when they figure out that's the only way their platform can boot :) thanks, greg k-h
