Messages in this thread | | | Date | Mon, 11 Mar 2013 11:55:52 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] x86, kdump: Set crashkernel_low automatically |
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On 03/11/2013 11:50 AM, Yinghai Lu wrote: >> >> What is the purpose of reserving that kind of memory below 896 MB? If >> you have a 32-bit system, it will likely be useless since you are >> robbing the primary of most of lowmem, on a 64-bit system 896 MB is not >> a magic value in any way...? > > We did not touch 32 bit system. > > Do you mean that we should > For 64bit, we should try under 4G, and then try MAXMEM > instead of try under 896M, then 4G, and MAXMEM? > > Try 896M at first, we will let user to avoid updating their kexec-tools. >
Are you saying 896M is somehow hardcoded into kexec-tools?
I actually disagree with trying low memory at all. Push kdump as high into the memory range as we can go, if there is a performance penalty it is much better to take it in the kdump kernel.
All the voodoo to try to keep people from updating kexec-tools is disturbing; although breaking userspace is bad, updating kexec-tools is probably easier than updating the kernel, and carrying the voodoo on indefinitely has serious consequences.
-hpa
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