Messages in this thread | | | From | KOSAKI Motohiro <> | Date | Mon, 13 Jan 2014 15:31:04 -0500 | Subject | Re: [PATCH 2/2] x86, e820 disable ACPI Memory Hotplug if memory mapping is specified by user [v2] |
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On Sun, Jan 12, 2014 at 6:46 PM, Prarit Bhargava <prarit@redhat.com> wrote: > > > On 01/11/2014 11:35 AM, 7eggert@gmx.de wrote: >> >> >> On Fri, 10 Jan 2014, Prarit Bhargava wrote: >> >>> kdump uses memmap=exactmap and mem=X values to configure the memory >>> mapping for the kdump kernel. If memory is hotadded during the boot of >>> the kdump kernel it is possible that the page tables for the new memory >>> cause the kdump kernel to run out of memory. >>> >>> Since the user has specified a specific mapping ACPI Memory Hotplug should be >>> disabled in this case. >> >> I'll ask just in case: Is it possible to want memory hotplug in spite of >> using memmap=exactmap or mem=X? > > Good question -- I can't think of a case. When a user specifies "memmap" or > "mem" IMO they are asking for a very specific memory configuration. Having > extra memory added above what the user has specified seems to defeat the purpose > of "memmap" and "mem".
May be yes, may be no.
They are often used for a wrokaround to avoid broken firmware issue. If we have no way to explicitly enable hotplug. We will lose a workaround.
Perhaps, there is no matter. Today, memory hotplug is only used on high-end machine and their firmware is carefully developped and don't have a serious issue almostly. Though.
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