On Fri, Nov 7, 2025 at 6:36 PM Yanjun.Zhu <[email protected]> wrote: > > > On 11/7/25 4:02 AM, Pasha Tatashin wrote: > > On Fri, Nov 7, 2025 at 7:00 AM Pasha Tatashin <[email protected]> > > wrote: > >>> Hi, Pasha > >>> > >>> In our previous discussion, we talked about counting the number of times > >>> the kernel is rebooted via kexec. At that time, you suggested adding a > >>> variable in debugfs to keep track of this count. > >>> However, since debugfs is now optional, where would be an appropriate > >>> place to store this variable? > >> It is an optional config and can still be enabled if the live update > >> reboot number value needs to be accessed through debugfs. However, > >> given that debugfs does not guarantee a stable interface, tooling > >> should not be built to require these interfaces. > >> > >> In the WIP LUO [1] I have, I pr_info() the live update number during > >> boot and also store it in the incoming LUO FDT tree, which can also be > >> accessed through this optional debugfs interface. > >> > >> The pr_info message appears like this during boot: > >> [ 0.000000] luo: Retrieved live update data, liveupdate number: 17 > >> > >> Pasha > > Forgot to add link to WIP LUOv5: > > [1] https://github.com/soleen/linux/tree/luo/v5rc04 > > > Thanks a lot. I’ve carefully read this commit: > https://github.com/soleen/linux/commit/60205b9a95c319dc9965f119303a1d83f0ff08fa. > > To be honest, I’d like to run some tests with who/luo, including the > selftest for kho/luo. Could you please share the steps with me? > > If the testing steps have already been documented somewhere, could you > please share the link?
Currently the test performs in-kernel tests for FLB data, it creates a number of FLB for every registered LUO file-handler, which at the moment is only memfd. It works together with any of the kexec based live update tests. In v5, I introduce two tests: luo_kexec_simple luo_multi_session For example, with luo_multi_session: # ./luo_multi_session # [STAGE 1] Starting pre-kexec setup for multi-session test... # [STAGE 1] Creating state file for next stage (2)... # [STAGE 1] Creating empty sessions 'multi-test-empty-1' and 'multi-test-empty-2'... # [STAGE 1] Creating session 'multi-test-files-1' with one memfd... # [STAGE 1] Creating session 'multi-test-files-2' with two memfds... # [STAGE 1] Executing kexec... ... reboot ... After reboot: $ ./luo_multi_session # [STAGE 2] Starting post-kexec verification... # [STAGE 2] Retrieving all sessions... # [STAGE 2] Verifying contents of session 'multi-test-files-1'... # [STAGE 2] Verifying contents of session 'multi-test-files-2'... # [STAGE 2] Test data verified successfully. # [STAGE 2] Finalizing all test sessions... # [STAGE 2] Finalizing state session... # --- MULTI-SESSION KEXEC TEST PASSED --- Dmesg data, shows that in-kernel live update test was also successful: [ 0.000000] luo: Retrieved live update data, liveupdate number: 1 [ 0.034513] liveupdate test: test-flb-v0: found flb data from the previous boot [ 0.034517] liveupdate test: test-flb-v1: found flb data from the previous boot [ 0.034518] liveupdate test: test-flb-v2: found flb data from the previous boot [ 0.676891] liveupdate test: Registered 3 FLBs with file handler: [memfd-v1] Pasha > Best Regards, > > Yanjun.Zhu >
