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@@ -149,6 +149,87 @@ cryptomount command from `for` loop in libreboot's It could be fixed in upstream grub by contributing patch that would add quiet flag to it. +How to save kernel panic logs on thinkpad laptops? +-------------------------------------------------- + +The easiest method of doing so is by using the kernel's netconsole +and reproducing the panic. Netconsole requires two machines, the one that is +panicky (source) and the one that will receive crash logs (target). The +source has to be connected with an ethernet cable and the target has to be +reachable at the time of the panic. To set this system up, execute the +following commands as root on the source (`source#`) and normal user on +the target (`target$`): + +1. Start a listener server on the target machine (netcat works well): + + `target$ nc -u -l -p 6666` + +2. Mount configfs (only once per boot, you can check if it is already mounted + with `mount | grep /sys/kernel/config`. This will return no output + if it is not). + + `source# modprobe configfs` + + `source# mkdir -p /sys/kernel/config` + + `source# mount none -t configfs /sys/kernel/config` + +3. find source's ethernet interface name, it should be of the form `enp*` or + `eth*`, see `ip address` or `ifconfig` output. + + `source# iface="enp0s29f8u1"` change this + + Fill the target machine's IPv4 address here: + + `source# tgtip="192.168.1.2"` change this + + +3. Create netconsole logging target on the source machine: + + `source# modprobe netconsole` + + `source# cd /sys/kernel/config/netconsole` + + `source# mkdir target1; cd target1` + + `source# srcip=$(ip -4 addr show dev "$iface" | grep -Eo '[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+')` + + `source# echo "$srcip" > local_ip` + + `source# echo "$tgtip" > remote_ip` + + `source# echo "$iface" > dev_name` + + `source# arping -I "$iface" "$tgtip" -f | grep -o '..:..:..:..:..:..' > remote_mac` + + `source# echo 1 > enabled` + +4. Change console loglevel to debugging: + + `source# dmesg -n debug` + +5. Test if the logging works by e.g. inserting or removing an USB + device on the source. There should be a few lines appearing in the + terminal, in which you started netcat (nc), on the target host. + +6. Try to reproduce the kernel panic. + +Machine check exceptions on some Montevina (Penryn CPU) laptops +--------------------------------------------------------------- + +Some GM45 laptops have been freezing or experiencing a kernel panic +(blinking caps lock LED and totaly unresponsive machine, sometimes followed +by an automatic reboot within 30 seconds). +We do not know what the problem(s) is(are), but a CPU microcode +update in some cases prevents this from happening again. +See the following bug reports for more info: + +- [T400 Machine check: Processor context corrupt](https://notabug.org/libreboot/libreboot/issues/493) +- [X200 Machine check: Processor context corrupt](https://notabug.org/libreboot/libreboot/issues/289) + +- [Unrelated, RAM incompatibility and suspend-to-ram issues on X200](https://libreboot.org/docs/hardware/x200.html#ram_s3_microcode) + + Hardware compatibility ====================== |