linux-kernel - Re: [PATCH v2 0/3] Expose recovery/coredump configuration from sysfs

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Message-ID: <944061c55a14e28b2a200215c21a9c39@codeaurora.org>
Date:   Wed, 02 Sep 2020 16:14:19 -0700
From:   rishabhb@...eaurora.org
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        bjorn.andersson@...aro.org, tsoni@...eaurora.org,
        psodagud@...eaurora.org, sidgup@...eaurora.org,
        linux-remoteproc-owner@...r.kernel.org
Subject: Re: [PATCH v2 0/3] Expose recovery/coredump configuration from sysfs

On 2020-09-01 15:05, Mathieu Poirier wrote:
> Hi Rishabh,
> 
> On Thu, Aug 27, 2020 at 12:48:48PM -0700, 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.
> 
> What I meant wast to move the coredump entry from debugfs to sysfs and 
> from
> there make it available to user space using a kernel config.  But 
> thinking
> further on this it may be better to simply provide an API to set the 
> coredump
> mode from the platform driver, the same way 
> rproc_coredump_set_elf_info() works.
> That will prevent breaking a fair amount of user space code...
> 
> Let me know if that can work for you.
> 
> Thanks,
> Mathieu
> 
Hi Mathieu,
That works for product configuration but that would still limit internal
testing. Since there is also restriction on accessing debugfs through
userspace code, automation won't be able to run recovery/coredump tests.
Only other way for us would be to provide these sysfs entries through 
the
platform drivers locally but that would create a lot of mess/redundancy.

>> '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.
>> 
>> 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(-)
>> 
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project
>>