linux-kernel - RE: [PATCH - resend] Memory-Hotplug: Fix the bug on interface /dev/mem for 64-bit kernel(v1)

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Message-ID: <DA586906BA1FFC4384FCFD6429ECE86031560C27@shzsmsx502.ccr.corp.intel.com>
Date:	Fri, 8 Jan 2010 13:18:01 +0800
From:	"Zheng, Shaohui" <shaohui.zheng@...el.com>
To:	"H. Peter Anvin" <hpa@...nel.org>
CC:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	"y-goto@...fujitsu.com" <y-goto@...fujitsu.com>,
	Dave Hansen <haveblue@...ibm.com>,
	"Wu, Fengguang" <fengguang.wu@...el.com>,
	"x86@...nel.org" <x86@...nel.org>
Subject: RE: [PATCH - resend] Memory-Hotplug: Fix the bug on interface
 /dev/mem for 64-bit kernel(v1)

Thanks Peter, my testing shows that there are many issues on 32-bit kernel for memory hot-add, there are still more works to do for 32-bit kernels(more than 2 patches). Memory hot-add is much more important on 64-bit kernel, I think that we can fix the bug on 64-bit kernel first. 32-kernel hotplug is the working in next step.

Thanks & Regards,
Shaohui


-----Original Message-----
From: H. Peter Anvin [mailto:hpa@...nel.org] 
Sent: Friday, January 08, 2010 1:03 PM
To: Zheng, Shaohui
Cc: linux-mm@...ck.org; akpm@...ux-foundation.org; linux-kernel@...r.kernel.org; ak@...ux.intel.com; y-goto@...fujitsu.com; Dave Hansen; Wu, Fengguang; x86@...nel.org
Subject: Re: [PATCH - resend] Memory-Hotplug: Fix the bug on interface /dev/mem for 64-bit kernel(v1)

On 01/07/2010 07:32 PM, Zheng, Shaohui wrote:
> Resend the patch to the mailing-list, the original patch URL is 
> http://patchwork.kernel.org/patch/69075/, 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
environments.

	-hpa