linux-kernel - Re: [POC] Extend "movable_node" to "movable_node=nn@ss" and add the interface in /sys to show the value

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Message-ID: <20171011084215.GB9142@x1>
Date:   Wed, 11 Oct 2017 16:42:15 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Chao Fan <fanc.fnst@...fujitsu.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-acpi@...r.kernel.org, hpa@...or.com, tglx@...utronix.de,
        mingo@...hat.com, keescook@...omium.org, arnd@...db.de,
        dyoung@...hat.com, dave.jiang@...el.com, lv.zheng@...el.com,
        rjw@...ysocki.net, yasu.isimatu@...il.com,
        caoj.fnst@...fujitsu.com, lizhijian@...fujitsu.com
Subject: Re: [POC] Extend "movable_node" to "movable_node=nn@ss" and add the
 interface in /sys to show the value

Hi dear Fan San,

On 10/11/17 at 04:23pm, Chao Fan wrote:
> On Wed, Oct 11, 2017 at 03:55:13PM +0800, Baoquan He wrote:
> >Hi Fan San,
> >> 1. Get and parse the srat table before kernel extracted, then mark the memory
> >>    region in movable node which should be avoided in kaslr.
> >>    I have send the patch:
> >>    https://www.spinics.net/lists/kernel/msg2595546.html
> >>    But the change is large and then here is the second method.
> >> 
> >> 2. Extend the movable_node to movable_node=nn@ss, in which nn means
> >>    the size of memory in immovable node, and ss means the start position of
> >>    this memory region.
> >>    But it brings another question, it may be a little difficult for a normal
> >>    user to specify the nn and ss. Because it's hard for a user to know the value
> >>    of the memory in immovable node.
> >>    So I wonder if it's good to add a interface in /sys, like:
> >>    # cat /sys/device/system/memory/immovable_node
> >
> Hi Baoquan,
> 
> Thanks for your reply,
> 
> >You can post patch. By the way, can the existing
> >/sys/devices/system/memory/memoryX/removable be used instead?
> 
> I ever search the interfaces of /sys/devices/system/memory/, and noticed
> this "removable", it does be able to help us judge it's removable or not.
> But we should also get the information of the memory length and start position
> by other interface. If there is a interface that show the nn and ss, we
> can use them and change grub directly.
> And there are more "memoryX" in one node. In my machine, I can see
> memory0(linked to /sys/devices/system/memory/memory0) - memory7 in
> /sys/devices/system/node/node0. And total memory38 for 4 nodes. I think
> it's a little heavy to handle every memoryX.
> But in SRAT table, one node has one or two memory regions. So I thinks
> it's more straight and easy to use. How do you think about it?

I am fine, I just mention it.

Then please show your code envelopped in well formatted patch.

Thanks
Baoquan

> >
> >>    nn@ss
> >>    nn@ss
> >>    ...
> >>    to show the two value.
> >>    When srat table is parsed in acpi_parse_memory_affinity, fill the value
> >>    and user can get and use them.
> >> 
> >> If anyone has a better method, please let me know.
> >> Any comments will be welcome.
> >> 
> >> Thanks,
> >> Chao Fan
> >> 
> >> 
> >
> >
> 
>