From: Gerd Hoffmann <kraxel@redhat.com>
To: Eduardo Habkost <ehabkost@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
qemu-devel@nongnu.org, Richard Henderson <rth@twiddle.net>
Subject: Re: [Qemu-devel] [PATCH v2] pc: allow raising low memory via max-ram-below-4g option
Date: Wed, 20 Jan 2016 15:55:33 +0100 [thread overview]
Message-ID: <1453301733.11804.142.camel@redhat.com> (raw)
In-Reply-To: <20160119123739.GA27855@thinpad.lan.raisama.net>
Hi,
> > + * qemu -M pc,max-ram-below-4g=2G -m 4G -> 2048M low, 2048M high
> I assume max-ram-below-4g > 3.5G was unsupported before, and we
> are breaking compatibility intentionally.
max-ram-below-4g did only reduce memory, so max-ram-below-4g > 3.5G (or
max-ram-below-4g > 3G with gigabyte align) had no effect and therefore
is something pretty pointless.
I'd expect the one case quoted above to be the only case relevant in
practice (i.e. move split from 3G to 2G for more PCI I/O space),
especially given that the option was added after gigabyte alignment
support.
> Because this patch also
> changes the resulting memory layout when
> 3G < max_ram_below_4g < ram_size < 3.5G
> e.g.:
> qemu -M pc,max-ram-below-4g=3200M -m 3328M
Ah, I see. With the patch applied the gigabyte align option is weighed
higher, so qemu wouldn't give you 3200M lowmem. I would be highly
surprised to see such a configuration in the wild ...
cheers,
Gerd
next prev parent reply other threads:[~2016-01-20 14:55 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-08 12:58 [Qemu-devel] [PATCH v2] pc: allow raising low memory via max-ram-below-4g option Gerd Hoffmann
2016-01-08 17:45 ` Igor Mammedov
2016-01-08 18:32 ` Laszlo Ersek
2016-01-11 8:26 ` Gerd Hoffmann
2016-01-11 12:16 ` Laszlo Ersek
2016-01-11 12:26 ` Marcel Apfelbaum
2016-01-14 23:45 ` Eric Blake
2016-01-19 12:37 ` Eduardo Habkost
2016-01-20 14:55 ` Gerd Hoffmann [this message]
2016-01-20 15:34 ` Eduardo Habkost
2016-01-20 17:15 ` Eduardo Habkost
2016-01-20 17:25 ` Michael S. Tsirkin
2016-01-21 7:48 ` Gerd Hoffmann
2016-01-21 9:37 ` Michael S. Tsirkin
2016-01-22 10:51 ` Gerd Hoffmann
2016-01-24 6:37 ` Michael S. Tsirkin
-- strict thread matches above, loose matches on Subject: below --
2016-06-02 8:48 Gerd Hoffmann
2015-11-03 10:06 Gerd Hoffmann
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