Messages in this thread | | | Date | Sun, 25 Jul 2004 23:57:05 -0700 | From | Andrew Morton <> | Subject | Re: Announce: dumpfs v0.01 - common RAS output API |
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Keith Owens <kaos@sgi.com> wrote: > > * How do we get a clean API to do polling mode I/O to disk?
We hope to not have to. The current plan is to use kexec: at boot time, do a kexec preload of a small (16MB) kernel image. When the main kernel crashes or panics, jump to the kexec kernel. The kexec kernel will hold a new device driver for /dev/hmem through which applications running under the kexec'ed kernel can access the crashed kernel's memory.
Write the contents of /dev/hmem to stable storage using whatever device drivers are in the kexeced kernel, then reboot into a real kernel again.
That's all pretty simple to do, and the quality of the platform's crash dump feature will depend only upon the quality of the platform's kexec support.
People have bits and pieces of this already - I'd hope to see candidate patches within a few weeks. The main participants are rddunlap, suparna and mbligh.
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