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Re: [RFC] fs: add userspace critical mounts event support

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On Fri 02 Sep 21:11 PDT 2016, Linus Torvalds wrote:

Linus, I reversed the order of your questions/answers to fit my answer
better.

> On Fri, Sep 2, 2016 at 5:20 PM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> >
> > Thoughts ?
> What are the drivers that need this, and why can't those drivers just
> be fixed to not do braindead things?
> 

I have several cases where remoteproc drivers are used boot DSPs upon
boot of the device, but the firmware files are way too big for being
stored in initramfs and all consumers of the provided services are
(semi-) probable as the remote processor is booted.

I.e. we need some way to figure out when these files become available so
we can bring these remote processors up.

> It's basically the kernel giving up, and relying on user space to give
> a single flag, and it's broken nasty crap.  Worse, it's broken nasty
> crap with a user interface, so we'll be stuck with it forever. Please
> no.
> 

There are several cases where there granularity of a single flag is not
enough and we do already have a working mechanism for relying on user
space to inform the kernel that firmware is available:
CONFIG_FW_LOADER_USER_HELPER_FALLBACK

Another available solution is, as you say, using kernel modules.  But I
really do not like the deployment issues that comes with kernel modules
during development. (The firmware and remoteproc driver normally does
not have the same flow through a development process)

> 
> I really think this is a horrible hack.
> 

I agree, but that said, I would appreciate a automagical mechanism that
would relieve user space from having to signal to the kernel that the
firmware partition has been mounted.

Regards,
Bjorn

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Re: [PATCH v2 2/5] firmware: annotate thou shalt not request fw on  init or probe Daniel Vetter <daniel.vetter@ffwll.ch> - 2016-08-25 13:10 +0200
  Re: [PATCH v2 2/5] firmware: annotate thou shalt not request fw on  init or probe "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-08-25 21:50 +0200
    Re: [PATCH v2 2/5] firmware: annotate thou shalt not request fw on  init or probe Daniel Vetter <daniel.vetter@ffwll.ch> - 2016-08-25 22:20 +0200
      Re: [PATCH v2 2/5] firmware: annotate thou shalt not request fw on  init or probe "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-08-25 22:30 +0200
    Re: [PATCH v2 2/5] firmware: annotate thou shalt not request fw on  init or probe Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-08-25 22:40 +0200
    Re: [PATCH v2 2/5] firmware: annotate thou shalt not request fw on  init or probe "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-09-03 02:00 +0200
      [RFC] fs: add userspace critical mounts event support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-09-03 02:30 +0200
        Re: [RFC] fs: add userspace critical mounts event support Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-03 06:20 +0200
          Re: [RFC] fs: add userspace critical mounts event support Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-09-03 06:30 +0200
            Re: [RFC] fs: add userspace critical mounts event support Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-09-03 20:00 +0200
              Re: [RFC] fs: add userspace critical mounts event support Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-09-03 20:20 +0200
                Re: [RFC] fs: add userspace critical mounts event support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-09-07 00:00 +0200
                Re: [RFC] fs: add userspace critical mounts event support Bjorn Andersson <bjorn.andersson@linaro.org> - 2016-09-07 00:30 +0200
                Re: [RFC] fs: add userspace critical mounts event support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-09-07 01:20 +0200
              Re: [RFC] fs: add userspace critical mounts event support Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-03 20:30 +0200
          Re: [RFC] fs: add userspace critical mounts event support Bjorn Andersson <bjorn.andersson@linaro.org> - 2016-09-06 19:50 +0200
            Re: [RFC] fs: add userspace critical mounts event support Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-06 20:40 +0200
              Re: [RFC] fs: add userspace critical mounts event support Bjorn Andersson <bjorn.andersson@linaro.org> - 2016-09-06 23:20 +0200
                Re: [RFC] fs: add userspace critical mounts event support Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-07 00:00 +0200
                Re: [RFC] fs: add userspace critical mounts event support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-09-07 01:10 +0200
              Re: [RFC] fs: add userspace critical mounts event support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-09-07 00:40 +0200

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