Re: [PATCH - resend] Memory-Hotplug: Fix the bug on interface /dev/memfor 64-bit kernel(v1)

From: Andi Kleen
Date: Fri Jan 08 2010 - 14:48:10 EST

H. Peter Anvin wrote:
On 01/07/2010 07:32 PM, Zheng, Shaohui wrote:
Resend the patch to the mailing-list, the original patch URL is, it is not accepted without comments,
sent it again to review.

Memory-Hotplug: Fix the bug on interface /dev/mem for 64-bit kernel

The new added memory can not be access by interface /dev/mem, because we do not
update the variable high_memory. This patch add a new e820 entry in e820 table,
and update max_pfn, max_low_pfn and high_memory.

We add a function update_pfn in file arch/x86/mm/init.c to udpate these
varibles. Memory hotplug does not make sense on 32-bit kernel, so we did not
concern it in this function.

Memory hotplug makes sense on 32-bit kernels, at least in virtual

No VM currently supports it to my knowledge. They all use traditional

If someone adds that they can still fix it, but right now fixing it on 64bit
is the important part.

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