On Tue, Mar 05, 2024 at 08:59:10PM -0500, Steven Rostedt wrote: > This is a way to map a ring buffer instance across reboots.
As mentioned on Fedi, check out the persistent storage subsystem (pstore)[1]. It already does what you're starting to construct for RAM backends (but also supports reed-solomon ECC), and supports several other backends including EFI storage (which is default enabled on at least Fedora[2]), block devices, etc. It has an existing mechanism for handling reservations (including via device tree), and supports multiple "frontends" including the Oops handler, console output, and even ftrace which does per-cpu recording and event reconstruction (Joel wrote this frontend). It should be pretty straight forward to implement a new frontend if the ftrace one isn't flexible enough. It's a bit clunky still to add one, but search for "ftrace" in fs/pstore/ram.c to see how to plumb a new frontend into the RAM backend. I continue to want to lift the frontend configuration options up into the pstore core, since it would avoid a bunch of redundancy, but this is where we are currently. :) -Kees [1] CONFIG_PSTORE et. al. in fs/pstore/ https://docs.kernel.org/admin-guide/ramoops.html [2] https://www.freedesktop.org/software/systemd/man/latest/systemd-pstore.service.html -- Kees Cook
