Hi Kim,

Thank you for your kindness. Let me clarify this:

On ARM architecture, there are 32 bits physical addresses space. However,
the addresses space is divided into 8 banks normally. Each bank
disabled/enabled by a chip selector signal. In my platform, bank0 connects
a DDR chip, and bank1 also connects another DDR chip. And each DDR chip
whose capability is 512MB is integrated into the main board. So, it could
not be removed by hand. We can disable/enable each bank by peripheral
device controller registers.

When system enter suspend state, if all the pages allocated could be
migrated to one bank, there are no valid data in the another bank. In this
time, I could disable the free bank. It isn't necessary to provided power
to this chip in the suspend state. When system resume, I just need to
enable it again.

Hi Wen,

I am sorry for that I doesn't know the "_PSx support" means. Maybe I
needn't it.

Thanks,
Jerry

2012/9/11 Minchan Kim [off-list ref]

Hi Jerry,

On Tue, Sep 11, 2012 at 08:27:40AM +0800, Jerry wrote:

quoted

Hi Wen,

I have been arranged a job related memory hotplug on ARM architecture.
Maybe I know some new issues about memory hotplug on ARM architecture. I
just enabled it on ARM, and it works well in my Android tablet now.
However, I have not send out my patches. The real reason is that I don't
know how to do it. Maybe I need to read

"Documentation/SubmittingPatches".

quoted

Hi Andrew,
This is my first time to send you a e-mail. I am so nervous about if I

have

quoted

some mistakes or not.

Don't be afraid.
If you might make a mistake, it's very natural to newbie.
I am sure anyone doesn't blame you. :)
If you have a good patch, please send out.

quoted

Some peoples maybe think memory hotplug need to be supported by special
hardware. Maybe it means memory physical hotplug. Some times, we just

need

quoted

to use memory logical hotplug, doesn't remove the memory in physical. It

is

quoted

also usefully for power saving in my platform. Because I doesn't want
the offline memory is in *self-refresh* state.

Just out of curiosity.
What's the your scenario and gain?
AFAIK, there were some effort about it in embedded side but gain isn't
rather big
IIRC.

quoted

Any comments are appreciated.

Thanks,
Jerry

2012/9/10 Vasilis Liaskovitis [off-list ref]

quoted

Hi,

On Mon, Sep 10, 2012 at 10:01:44AM +0800, Wen Congyang wrote:

quoted

At 09/10/2012 09:46 AM, Yasuaki Ishimatsu Wrote:

quoted

Hi Wen,

2012/09/01 5:49, Andrew Morton wrote:

quoted

On Tue, 28 Aug 2012 18:00:07 +0800
wency@cn.fujitsu.com wrote:

quoted

This patch series aims to support physical memory hot-remove.

I doubt if many people have hardware which permits physical memory
removal?  How would you suggest that people with regular hardware

can

quoted

quoted

quoted

quoted

quoted

test these chagnes?

How do you test the patch? As Andrew says, for hot-removing memory,
we need a particular hardware. I think so too. So many people may

want

quoted

quoted

quoted

quoted

to know how to test the patch.
If we apply following patch to kvm guest, can we hot-remove memory

on

quoted

quoted

quoted

quoted

kvm guest?

http://lists.gnu.org/archive/html/qemu-devel/2012-07/msg01389.html

Yes, if we apply this patchset, we can test hot-remove memory on kvm

guest.

quoted

But that patchset doesn't implement _PS3, so there is some

restriction.

quoted

quoted

the following repos contain the patchset above, plus 2 more patches

that

quoted

quoted

add
PS3 support to the dimm devices in qemu/seabios:

https://github.com/vliaskov/seabios/commits/memhp-v2
https://github.com/vliaskov/qemu-kvm/commits/memhp-v2

I have not posted the PS3 patches yet in the qemu list, but will post

them

quoted

quoted

soon for v3 of the memory hotplug series. If you have issues testing,

let

quoted

quoted

me
know.

thanks,

- Vasilis

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