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Re: [Qemu-devel] release retrospective, next release timing, numbering
From: |
Laszlo Ersek |
Subject: |
Re: [Qemu-devel] release retrospective, next release timing, numbering |
Date: |
Wed, 2 May 2018 12:41:21 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 |
On 04/29/18 16:56, Richard Henderson wrote:
> On 04/27/2018 02:01 PM, Michal Suchánek wrote:
>> Is there any reason why the 64bit emulator would not run on 32bit
>> system? The emulated 64bit system is .. emulated after all.
>
> It does run, but it requires that the 32-bit host perform double-word
> arithmetic to emulate the 64-bit guest. When the 64-bit guest is really a
> 32-bit guest in disguise, this carries a performance penalty.
>
> If we ever stop caring about 32-bit hosts, the question becomes moot.
What about guest RAM size (more precisely, guest-phys address space)?
The x86_64 target might want to use tens of GBs of guest-phys address
space, e.g. for cold-plugged RAM, for DIMM hotplug, for 64-bit PCI MMIO
aperture. To my understanding, all of those have to be expressed with
host virtual addresses in the QEMU process (regardless of TCG vs. KVM).
But on a 32-bit host, the QEMU process only has 4GB HVA space.
Thanks
Laszlo
- Re: [Qemu-devel] release retrospective, next release timing, numbering, (continued)
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Daniel P . Berrangé, 2018/05/03
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Kashyap Chamarthy, 2018/05/07
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Thomas Huth, 2018/05/07
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Cornelia Huck, 2018/05/03
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Kevin Wolf, 2018/05/04
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Thomas Huth, 2018/05/04
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Kevin Wolf, 2018/05/04
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Richard Henderson, 2018/05/04
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Thomas Huth, 2018/05/07
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Kevin Wolf, 2018/05/07
Re: [Qemu-devel] release retrospective, next release timing, numbering,
Laszlo Ersek <=
Re: [Qemu-devel] release retrospective, next release timing, numbering, Daniel P . Berrangé, 2018/05/02
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Peter Maydell, 2018/05/02
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Daniel P . Berrangé, 2018/05/03
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Thomas Huth, 2018/05/03
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Daniel P . Berrangé, 2018/05/03
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Cédric Le Goater, 2018/05/03
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Cédric Le Goater, 2018/05/03
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Stefan Hajnoczi, 2018/05/03
- Re: [Qemu-devel] release retrospective, next release timing, numbering, Dr. David Alan Gilbert, 2018/05/03