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

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Date:   Tue, 1 Sep 2020 16:05:42 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Rishabh Bhatnagar <rishabhb@...eaurora.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
Subject: Re: [PATCH v2 0/3] Expose recovery/coredump configuration from sysfs

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

> '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
>