On Thu, May 24, 2018 at 2:01 PM, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > 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 <robh@xxxxxxxxxx> >> --- >> .../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 :) Here's some rope... No doubt it can be abused. So are you saying don't call it a debug option or hide it behind a config option? And for the latter, what's one that distros don't just turn on? Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
