Re: [Xen-devel] Bug: Limitation of <=2GB RAM in domU persists with 4.3.0

[Gordan Bobic <gordan@xxxxxxxxxx>]

Attached are:

domU-2GB dmesg, lspci
domU-8GB dmesg, lspci

map-2GB - memory map, e820 + PCI
map-8GB - memory map, e820 + PCI

There are no overlaps. In fact, the map is identical with 2040MB and 
8192MB, except for the top usable range being bigger.
So according to this, there _shouldn't_ be any memory clobbering
going on within domU.

Which leads on to what George said earlier, which I will reply to in a 
separate email.
What puzzles me, however, is that I thought that in 4.3.0 all 64-bit 
BARs should automatically be re-mapped to memory > 4GB, and that doesn't 
appear to be happening here. Or is the remapping only happening if there 
is not enough 32-bit space for all the BARs?
Gordan

On 07/24/2013 05:31 PM, Konrad Rzeszutek Wilk wrote:
> On Wed, Jul 24, 2013 at 05:14:32PM +0100, Gordan Bobic wrote:
> > On Wed, 24 Jul 2013 12:06:39 -0400, Konrad Rzeszutek Wilk
> > <konrad.wilk@xxxxxxxxxx> wrote:
> >
> > > > > Are you also able to get the serial log from the guest? (IF this is
> > > > > Linux?) I usually have this in my guest config:
> > > > >
> > > > > serial='pty'
> > > > >
> > > > > and when Linux boots up I add 'console=ttyS0,115200 loglevel=8
> > > > debug'
> > > > > which will output everything to the 'xl console <guest> | tee
> > > > > /tmp/log'.
> > > > The intended guest is XP64. I will, however, get a Linux guest up
> > > Ah, I am not actually sure how Linux will work. I hadn't had a chance
> > > to test that recently :-(
> > As long as it brings up the serial console, that should be
> > sufficient, but working VNC to text console login would be
> > convenient. The main thing I want to find on it is the
> > BAR mapping addresses from lspci and compare that to the
> > e820 map from dmesg.
> I see. That should work for you.
> > I wouldn't expect the memory map provided by SeaBIOS and
> > the BAR mappings configured by qemu-dm to differ
> > depending on the domU OS. Or am I wrong here?
> They might. The patches to fix the 2GB limit went in qemu-xen-traditional
> meaning you have to use:
>
> device_model_version = 'qemu-xen-traditional'
>
> in your guest config (which I think you are already doing).
>
> I don't recall what the situation is with upstream SeaBIOS.
> > If there is any overlap, the problem should be obvious.
> > If there is no overlap, then something even more
> > bizzare is going on, but we can worry about that
> > later. :)

Attachment: edi2-dmesg.log.2GB
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Attachment: edi2-lspci.log.2GB
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Attachment: map.2GB
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Attachment: edi2-dmesg.log.8GB
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Attachment: edi2-lspci.log.8GB
Description: Text document

Attachment: map.8GB
Description: Text document

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