What's Inside a Linux Kernel Core Dump

> Like a more specialized piece of code that only handles kernel coredumps?

Can't the kdump kernel be exactly that?

You can build a second kernel separate from the normal one, that only has the necessary options enabled to handle the coredump stuff. This way it can be relatively small and you can reuse the required driver code.

That is in fact how crash dump works on illumos systems. Once you enter a kernel panic, interrupts are disabled, all other CPUs are brought to rest, etc. Then the panic code takes the pages to write to the dump and passes them to a special routine in the driver for the dump device: usually either a slice on a disk or a zvol). That driver is responsible for getting the device into a state where polled I/O can be performed, and to write the pages out. At the end the system reboots, and on the next boot a program called savecore inspects the dump device to see if there is a new dump, and if there is it transfers it into a new file.

> Is there really no better way to do this than to have an entire second kernel > ready to take over? Like a more specialized piece of code that only handles > kernel coredumps?

So the requirements of this software are: It must be able to boot a system, write to the specific sections of memory, have some method of initializing hardware, some ability to write the other memory to disk or network connections. It sounds like you're talking about an OS.

I believe this is exactly what KDUMP does.

OpenVMS on x86 implements kernel crash dumping in more or less the same way as Linux. See Chapter 6 of https://docs.vmssoftware.com/docs/vsi-openvms-x86-64-boot-ma...

For what it's worth, Oracle is one of the largest contributors to the kernel, especially if you filter out the drivers subtree, which tends to skew the metrics for various reasons (lots of large generated code, almost identical arm SoC variants etc)

It would be really odd if they couldn't teach you about the kernel.

As a counter-example, Zstd is created and primarily developed by a Meta employee.

I also felt the same way upon opening the article, but companies are made of individuals, and often individuals do valuable and insightful work, even inside of bureaucratic and Kafkaesque organizations like Oracle.

It's just you.

Feels wrong, but the information density and presentation are pretty good for this. Easy to understand I think.

A bit, but there's plenty of very smart people there, and this particular page seems controlled by the engineers and not the leadership.