On Mon, Nov 10, 2025 at 8:16 AM Pratyush Yadav <[email protected]> wrote: > > On Sun, Nov 09 2025, Zhu Yanjun wrote: > > > 在 2025/11/8 10:13, Pasha Tatashin 写道: > >> 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: > > > > Hi, Pasha > > > > I enabled "CONFIG_LIVEUPDATE=y" > > > > # ./luo_multi_session > > 1..0 # SKIP Failed to open /dev/liveupdate. Is the luo module loaded? > > > > # ls /dev/liveupdate > > ls: cannot access '/dev/liveupdate': No such file or directory > > > > # grep "LIVEUPDATE" -inrHI /boot/config-`uname -r` > > /boot/config-next-20251107-luo+:349:CONFIG_LIVEUPDATE=y > > /boot/config-next-20251107-luo+:11985:CONFIG_LIVEUPDATE_TEST=y > > > > I made tests on FC42. But /dev/liveupdate is missing. > > You need to add liveupdate=1 to your kernel cmdline to enable LUO and > get /dev/liveupdate.
+1, kernel parameters require: kho=1 liveupdate=1 > > Pasha, your LUO series doesn't add the liveupdate parameter to > kernel-parameters.txt. I think it should be done in the next version to > this parameter is discoverable. Yeah, that is missing, I will update that in a standalone patch, or in a next version. Thanks, Pasha
