On Fri, Jun 05, 2026 at 02:10:40PM +0200, Michal Clapinski wrote: > Up to this point to preserve late shutdown logs in memory, users had to > predefine a memory region using ramoops. This commit changes this by > preserving a buffer using kexec-handover. > > pstore_kho supports preserving only 1 dmesg buffer. > It gets replaced with the new buffer on every kexec, so the user has to > copy the file out of pstore after every kexec. > There is no erase() support. > > Signed-off-by: Michal Clapinski <[email protected]>
I'm a fan of the idea! I'd love to see a selftest added for this backend, since it should be possible to do a direct tests for dmesg preservation across a kexec in tools/testing/selftests/pstore/ There is still good feedback from sashiko, which caught everything I was going to mention and then some: https://sashiko.dev/#/patchset/20260605121040.1177072-1-mclapinski%40google.com > --- > v2: > - Added a comment explaining the benefits of pstore_kho. > - Created include/linux/kho/abi/pstore.h. > - Got rid of the KHO subtree. > - Made sure never to free incoming kho data. > This way the module can be safely reloaded. > - Sashiko complained that I trust the data coming from the old kernel. > I ignored it. LMK if I shouldn't trust the old kernel. We shouldn't trust the old kernel. :) Sashiko's suggestion here seems reasonable which is to at least bounds-check the size against RECORD_MAX_SIZE since that's the largest it should ever be. -Kees -- Kees Cook
