Re: [Xen-users] dynamic memory extension not working on Debian Squeeze

[Peter Viskup <skupko.sk@xxxxxxxxx>]

On 11/20/2012 06:43 PM, Ian Campbell wrote:
> On Tue, 2012-11-20 at 17:30 +0000, Alexandre Kouznetsov wrote:
> > I have attached the complete dmesg for a better reference. This one is
> > after I changed from "mem=8G" to "mem=8192M".
> It's interesting that it has both:
>          [    0.000000] BIOS-provided physical RAM map:
>          [    0.000000]  Xen: 0000000000000000 - 00000000000a0000 (usable)
>          [    0.000000]  Xen: 00000000000a0000 - 0000000000100000 (reserved)
>          [    0.000000]  Xen: 0000000000100000 - 0000000010000000 (usable)
>
> and
>          [    0.000000] user-defined physical RAM map:
>          [    0.000000]  user: 0000000000000000 - 00000000000a0000 (usable)
>          [    0.000000]  user: 00000000000a0000 - 0000000000100000 (reserved)
>          [    0.000000]  user: 0000000000100000 - 0000000010000000 (usable)
>
> Where I think the second one is the result of passing mem=, yet it is
> exactly the same! I suspect it has taken the command line provided limit
> and clamped it...
>
> Another thing you could try is using the memmap command line option to
> generate a memmap like those above but with the limit on the 3rd one ==
> 8G. You'll have to read Documentation/kernel-parameters.txt to figure
> out exactly how though since I'm not sure how that stuff works.
>
> Another workaround would be to boot with 8G and then balloon down ASAP.
> This means you need the spare RAM available to boot the guest though,
> which isn't ideal...
>
> Ian.
I was just followed this wiki [1] and found that these options/features 
are not available in Debian's domU paravirt_ops kernel (2.6.32-5-amd64):
CONFIG_PARAVIRT_SPINLOCKS (really needed?)
CONFIG_XEN_XENBUS_FRONTEND (available since 2.6.38)
Looks like that wiki needs rewrite and having more information about 
every kernel option would be great. Anyway I am quite tired of checking 
those kernel options and decided to open an bug report for it [2]. Will 
see what will happen.
[1] http://wiki.xensource.com/xenwiki/XenParavirtOps
[2] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=693851

--
Peter

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