Messages in this thread | | | Date | Fri, 2 Nov 2018 14:50:33 -0700 | From | Joel Fernandes <> | Subject | Re: [PATCH 7/8] pstore: Remove needless lock during console writes |
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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
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