On Thu, Oct 18, 2018 at 8:33 AM, Dan Williams <[email protected]> wrote: > [ add Ross ]
Hi Ross! :) > On Thu, Oct 18, 2018 at 12:15 AM Kees Cook <[email protected]> wrote: >> As for nvdimm specifically, yes, I'd love to get pstore hooked up >> correctly to nvdimm. How do the namespaces work? Right now pstore >> depends one of platform driver data, device tree specification, or >> manual module parameters. > > From the userspace side we have the ndctl utility to wrap > personalities on top of namespaces. So for example, I envision we > would be able to do: > > ndctl create-namespace --mode=pstore --size=128M > > ...and create a small namespace that will register with the pstore sub-system. > > On the kernel side this would involve registering a 'pstore_dev' child > / seed device under each region device. The 'seed-device' sysfs scheme > is described in our documentation [1]. The short summary is ndctl > finds a seed device assigns a namespace to it and then binding that > device to a driver causes it to be initialized by the kernel. > > [1]: https://www.kernel.org/doc/Documentation/nvdimm/nvdimm.txt Interesting! Really, this would be a way to configure "ramoops" (the persistent RAM backend to pstore), rather than pstore itself (pstore is just the framework). From reading the ndctl man page it sounds like there isn't a way to store configuration information beyond just size? ramoops will auto-configure itself and fill available space using its default parameters, but it might be nice to have a way to store that somewhere (traditionally it's part of device tree or platform data). ramoops could grow a "header", but normally the regions are very small so I've avoided that. I'm not sure I understand the right way to glue ramoops_probe() to the "seed-device" stuff. (It needs to be probed VERY early to catch early crashes -- ramoops uses postcore_initcall() normally.) Thanks for the pointers! -Kees -- Kees Cook Pixel Security
