On Tue, 10 Sep 2019 at 10:20, Paul Thomas <pthomas8589@xxxxxxxxx> wrote: > > Hello, 'last' is a handy tool, and using it for > 'last reboot' provides a nice log. > > I was wondering if there are currently any platforms where more > information about the reboot type is supported? For instance on the > Zynq UltraScale+ devices there are a variety of reboot reasons: > https://www.xilinx.com/html_docs/registers/ug1087/crl_apb___reset_reason.html# > > So on each startup the reason could be read and logged before > resting the register[1]. > > I guess one tricky issue would be the kernel interface, > for a test I was just using memtool like this: > # memtool md 0xFF5E0220+1 > ff5e0220: 00000001 > > Where 00000001 indicates an 'External POR', but this probably > isn't how we'd want to do it. > > I'm not subscribed to the mailing-list so please cc me any response. > > thanks, > Paul > > [1] If the register is not reset then multiple bits can accumulate > so you wouldn't now which is correct for the current boot Hi Paul The last(1) is pretty simple tool. It can and will display information tracked in utmp(5) data. http://man7.org/linux/man-pages/man5/utmp.5.html The utmp data is stored over many many reboots, that might stay around for years. Notice that changing utmp(5) is probably not the easiest thing to achieve. That format is part of POSIX. Assuming standards are changed then update to various libc implementations is needed as well. Alternatively some sort of extented-utmp format could be created to avoid standardization work, but getting that to adopted might be hard. While utmp has it's flaws it is not exactly broken. In short while I'm not strictly against better reboot reason tracking I am a somewhat doubtful how feasible this work is. That said what is that memtool? I have never noticed it before. By glance it looks a little like abandonware. Maybe it could be get a home in util-linux if a tool like that is found to be useful, and old maintainer does not mind. -- Sami Kerola http://www.iki.fi/kerolasa/
