From: Joel Fernandes <joel@joelfernandes.org>
To: Kees Cook <keescook@chromium.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Anton Vorontsov <anton@enomsg.org>,
Colin Cross <ccross@android.com>, Tony Luck <tony.luck@intel.com>
Subject: Re: [PATCH 7/8] pstore: Remove needless lock during console writes
Date: Fri, 2 Nov 2018 14:50:33 -0700 [thread overview]
Message-ID: <20181102215033.GA99294@google.com> (raw)
In-Reply-To: <CAGXu5jKNjipB2yWf_7pE+m29Ma8KUOXotz2L=Pc7=wBZC3AGdA@mail.gmail.com>
On Fri, Nov 02, 2018 at 01:40:06PM -0700, Kees Cook wrote:
> On Fri, Nov 2, 2018 at 11:32 AM, Joel Fernandes <joel@joelfernandes.org> wrote:
> > On Thu, Nov 01, 2018 at 04:51:59PM -0700, Kees Cook wrote:
> >> Since commit 70ad35db3321 ("pstore: Convert console write to use
> >> ->write_buf"), the console writer does not use the preallocated crash
> >> dump buffer any more, so there is no reason to perform locking around it.
> >
> > Out of curiosity, what was the reason for having this preallocated crash
> > buffer in the first place? I thought the 'console' type only did regular
> > kernel console logging, not crash dumps.
>
> The primary reason is that the dumper needs to write to somewhere and
> we don't know the state of the system (memory allocation may not work
> for example).
>
> The other frontends tend to run at "sane" locations in the kernel. The
> dumper, however, is quite fragile.
Makes sense. thanks.
> > Also I wonder if Namhyung is still poking around that virtio pstore driver he
> > mentioned in the commit mentioned above. :)
>
> Did that never land? I thought it mostly had to happen at the qemu end?
>
> With nvdimm emulation, we can just use ramoops. :)
>
Yes it seems like it never landed: https://lwn.net/Articles/694742/
One of the nice thing about his virtio set though, vs the nvdimm way is that
he actually gets a directory on the host instead of a backing memory file.
Then he can just list this directory and see all the pstore files as he shows
in his example.
I guess it should not be too hard to write a tool to post-process the nvdimm
images and convert it to files anyway :)
thanks,
- Joel
next prev parent reply other threads:[~2018-11-02 21:50 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-01 23:51 [PATCH 0/8] pstore improvements (pstore-next) Kees Cook
2018-11-01 23:51 ` [PATCH linux-next 1/8] pstore/ram: Standardize module name in ramoops Kees Cook
2018-11-01 23:51 ` [PATCH 2/8] pstore: Do not use crash buffer for decompression Kees Cook
2018-11-02 18:24 ` Joel Fernandes
2018-11-14 7:56 ` Kees Cook
2018-11-20 21:43 ` Joel Fernandes
2018-11-29 22:06 ` Kees Cook
2018-11-30 2:26 ` Joel Fernandes
2018-11-01 23:51 ` [PATCH 3/8] pstore/ram: Report backend assignments with finer granularity Kees Cook
2018-11-01 23:51 ` [PATCH 4/8] pstore/ram: Add kern-doc for struct persistent_ram_zone Kees Cook
2018-11-01 23:51 ` [PATCH 5/8] pstore: Improve and update some comments and status output Kees Cook
2018-11-01 23:51 ` [PATCH 6/8] pstore: Replace open-coded << with BIT() Kees Cook
2018-11-01 23:51 ` [PATCH 7/8] pstore: Remove needless lock during console writes Kees Cook
2018-11-02 18:32 ` Joel Fernandes
2018-11-02 20:40 ` Kees Cook
2018-11-02 21:50 ` Joel Fernandes [this message]
2018-11-01 23:52 ` [PATCH 8/8] pstore/ram: Correctly calculate usable PRZ bytes Kees Cook
2018-11-02 18:01 ` Joel Fernandes
2018-11-02 20:00 ` Kees Cook
2018-11-05 4:42 ` Joel Fernandes
2018-11-05 17:04 ` Kees Cook
2018-11-06 4:42 ` Joel Fernandes
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