Re: [PATCH 0/3] Cleanup kdump memmap= passing and e820 usage

Eric W. Biederman
2013-01-30T18:53:05Z

"H. Peter Anvin" <hpa@zytor.com> writes:

> I have to admit to being rather confused as to the separation of various bits of
> kdump between the host kernel and various user-space components, but the whole
> use of the command line to pass the memory map seems just broken in light of
> everything that can go wrong.

It certainly seems time to look at this design decision and see if it
still makes sense.

The original idea was to pass the e820 map in the e820 variables, and to
slightly override that map to report which memory it was safe for the
kdump kernel to run in. Leaving the kernel with the knowledge that
of where everything actually is, and that we just don't happen to be
using all of the memory.

Now something seems to have gone wrong with that strategy as we wound
up needing to play games with acpi and gart addresses.

I see one of two very basic options going forward.
- Pass a kernel command line option that just changes the kernels idea
of which memory it can touch (and we can remove all of the other options).
- Modify the e820 map we pass to the kdump kernel and don't bother to
pass anything on the command line.

Eric