I vaguely remember a kernel extension where the last few KB of logging was saved to some ram on suitable motherboards. This let you recover the dump from an oops/panic on the next boot. Very useful for server farms.
Does anyone remember what that extension was called? Or the motherboard feature to have that storage.
Is there a way to set aside some RAM and save it there instead (for an embedded system)?
Originally this was the feature of Android kernel called RAM console. It can be enabled using CONFIG_ANDROID_RAM_CONSOLE option.
Now the similar mechanism called pstore is available in mainline kernel (was added by this commit). You can enable it using CONFIG_PSTORE_* options.
More details about RAM console upstreaming can be found here.