Re: [patch 0/3] memory hotplug prototype

From: IWAMOTO Toshihiro
Date: Thu Apr 08 2004 - 21:38:49 EST


At Thu, 08 Apr 2004 09:56:35 -0700,
Martin J. Bligh <mbligh@xxxxxxxxxxx> wrote:
>
> > At Wed, 07 Apr 2004 11:12:55 -0700,
> > Martin J. Bligh <mbligh@xxxxxxxxxxx> wrote:
> >>
> >> > This is an updated version of memory hotplug prototype patch, which I
> >> > have posted here several times.
> >>
> >> I really, really suggest you take a look at Dave McCracken's work, which
> >> he posted as "Basic nonlinear for x86" recently. It's going to be much
> >> much easier to use this abstraction than creating 1000s of zones ...
> >
> > Well, I think his patch is orthogonal to mine. My ultimate target
> > is IA64 and it will only support node-sized memory hotplugging.
>
> Are you saying you're only creating a patch for ia64 only, rather than
> an arch-independant one?

I'm not trying to make my patches IA64 specific, and my patch is quite
machine independent. However, some of them, such as placing mem_map at
boot time or hotplug events, are machine dependent by nature.

I'm afraid that the memsection thing is overkill for systems whose
hotpluggable memory unit is large. I understand there's need for
memsection, but I think that should be optional.

BTW, I think memory hotplugging on 32 bit archs are difficult because
of their narrow address space. For example:
1. A system boots with 1GB * 4 blocks of RAM.
2. The second RAM block is removed.
3. A 2GB block is inserted in the second slot.
Where does these RAM block appear in physical space, and where should
their mem_map be placed?

--
IWAMOTO Toshihiro


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