Hi Bjorn, On 9/26/20 5:31 AM, Bjorn Andersson wrote: > On Tue 15 Sep 02:51 PDT 2020, Arnaud POULIQUEN wrote: > >> Hi Rishabh, >> >> On 8/27/20 9:48 PM, Rishabh Bhatnagar wrote: >>> From Android R onwards Google has restricted access to debugfs in user >>> and user-debug builds. This restricts access to most of the features >>> exposed through debugfs. This patch series adds a configurable option >>> to move the recovery/coredump interfaces to sysfs. If the feature >>> flag is selected it would move these interfaces to sysfs and remove >>> the equivalent debugfs interface. 'Coredump' and 'Recovery' are critical >>> interfaces that are required for remoteproc to work on Qualcomm Chipsets. >>> Coredump configuration needs to be set to "inline" in debug/test build >>> and "disabled" in production builds. Whereas recovery needs to be >>> "disabled" for debugging purposes and "enabled" on production builds. >> >> The remoteproc_cdev had been created to respond to some sysfs limitations. > > The limitation here is in debugfs not being available on all systems, > sysfs is present and I really do like the idea of being able to change > these things without having to compile a tool to invoke the ioctl... Right, > >> I wonder if this evolution should not also be implemented in the cdev. >> In this case an additional event could be addedd to inform the application >> that a crash occurred and that a core dump is available. >> > > Specifically for userspace to know when a coredump is present there's > already uevents being sent when the devcoredump is ready. That said, > having some means to getting notified about remoteproc state changes > does sounds reasonable. If there is a use case we should discuss that. The main use case i have in mind is to inform the userspace that the remote processor has crashed. This would allow applications to perform specific action to avoid getting stuck and/or resetting it's environement befor restarting the remote processor and associated IPC. If i well remember QCOM has this kind of mechanism for its modem but this is implemented in a platform driver. We would be interested to have something more generic relying on the remoteproc framework. Thanks, Arnaud > >> Of course it's only a suggestion... As it would be a redesign. > > A very valid suggestion. I don't think it's a redesign, but more of an > extension of what we have today. > > Regards, > Bjorn > >> I let Björn and Mathieu comment. >> >> Regards, >> Arnaud >> >>> >>> Changelog: >>> >>> v1 -> v2: >>> - Correct the contact name in the sysfs documentation. >>> - Remove the redundant write documentation for coredump/recovery sysfs >>> - Add a feature flag to make this interface switch configurable. >>> >>> Rishabh Bhatnagar (3): >>> remoteproc: Expose remoteproc configuration through sysfs >>> remoteproc: Add coredump configuration to sysfs >>> remoteproc: Add recovery configuration to sysfs >>> >>> Documentation/ABI/testing/sysfs-class-remoteproc | 44 ++++++++ >>> drivers/remoteproc/Kconfig | 12 +++ >>> drivers/remoteproc/remoteproc_debugfs.c | 10 +- >>> drivers/remoteproc/remoteproc_sysfs.c | 126 +++++++++++++++++++++++ >>> 4 files changed, 190 insertions(+), 2 deletions(-) >>>
