Re: [Qemu-devel] [Bug 596106] Re: kvm to emulate 64 bit cpu on 32 bit host
On 06/19/2010 01:53 AM, Iggy wrote: KVM isn't an emulator. It virtualizes the CPU. A 32bit CPU can't be forced to run as a 64bit cpu. This is a wontfix. qemu actually supports this (32-bit qemu can run a 64-bit guest with kvm, provided that the kernel is 64-bit). So as well as a wontfix, it's filed in the wrong tracker. -- error compiling committee.c: too many arguments to function
Re: [Qemu-devel] [Bug 596106] Re: kvm to emulate 64 bit cpu on 32 bit host
Natalia Portillo wrote: You got the point wrong, I'm talking running WITH 64 bit hardware in a 32 bit guest. This is done in Mac OS X Leopard (kernel is only 32 bit) and Mac OS X Snow Leopard (using 32 bit kernel not 64 bit one) by VMWare, Parallels and VirtualBox, as well as on Windows 32 bit using VMWare (dunno about VBox and Parallels, VirtualPC is unable to run 64 bit guests at all even on 64 bit hosts), just provided of course, the hardware is 64 bit. Ah yes, Mac OS X too. Apart from breaking userspace, the other reason people stick with 32-bit host kernels on both Windows and Macs is the 64-bit device drivers often don't work properly, or aren't available at all. They continue to improve, but still aren't as mature and dependable as 32-bit drivers. This is also true of Linux 64-bit kernels - both bugs and unavailable third party drivers/firmware. (But less so than the other OSes.) So even with Linux people cannot assume dropping in a 64-bit host kernel is always free of kernel/driver issues. Marking this feature request won't fix is just a statement that KVM developers aren't inclined to support this feature. But there's nothing to stop an interested contributor having a go. I'm sure if it works and the code is clean enough it will be accepted. VirtualPC is unable to run 64 bit guests at all even on 64 bit hosts Are you sure? Microsoft provides numerous downloadable 64-bit guest Windows images, and VirtualPC is Microsoft's; they must be running on something. -- Jamie
Re: [Qemu-devel] [Bug 596106] Re: kvm to emulate 64 bit cpu on 32 bit host
Paolo said: They do it like TCG does it, not like KVM. You are wrong, and it's easy to check as the speed is almost native. Having emulation would make it slow as hell. Jamie said: VirtualPC is unable to run 64 bit guests at all even on 64 bit hosts Are you sure? Microsoft provides numerous downloadable 64-bit guest Windows images, and VirtualPC is Microsoft's; they must be running on something. That may be in Windows Virtual PC (that requires VT and Windows 7 Ultimate/Professional, and is a feature of that OSes not a separate product) or Hyper-V (again, requires VT and is a feature of Windows 2008 Server), but not on the standalone Microsoft Virtual PC 2007. It is fully possible to run 64-bit code in a 32-bit kernel, Mac OS X Leopard does that all the way without problems, and VMWare found how to do the trick with the NT kernel. The question is not is it possible to make KVM run 64-bit code in a 32-bit kernel? (it is), the question is, the people in charge of KVM want to add this feature?. Personally I don't believe so, neither I am on the do it side, I'm just saying it is technically possible. Natalia Portillo
Re: [Qemu-devel] [Bug 596106] Re: kvm to emulate 64 bit cpu on 32 bit host
- Natalia Portillo clau...@claunia.com wrote: From: Natalia Portillo clau...@claunia.com To: qemu-devel@nongnu.org Sent: Saturday, June 19, 2010 9:01:04 AM GMT -05:00 US/Canada Eastern Subject: [Qemu-devel] [Bug 596106] Re: kvm to emulate 64 bit cpu on 32 bit host VMWare is able to do it, we should be able. VMware can't do that! To run a 64bit guest on VMware you need 64bit hardware and VT/AMD-V http://kb.vmware.com/selfservice/microsites/search.do?language=en_UScmd=displayKCexternalId=1003945 -- kvm to emulate 64 bit cpu on 32 bit host https://bugs.launchpad.net/bugs/596106 You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. Status in QEMU: Won't Fix Bug description: i wish kvm can run 64bit guest os on 32bit host just like qemu does.
Re: [Qemu-devel] [Bug 596106] Re: kvm to emulate 64 bit cpu on 32 bit host
El 19/06/2010, a las 22:12, Andrew Cathrow escribió: - Natalia Portillo clau...@claunia.com wrote: From: Natalia Portillo clau...@claunia.com To: qemu-devel@nongnu.org Sent: Saturday, June 19, 2010 9:01:04 AM GMT -05:00 US/Canada Eastern Subject: [Qemu-devel] [Bug 596106] Re: kvm to emulate 64 bit cpu on 32 bit host VMWare is able to do it, we should be able. VMware can't do that! To run a 64bit guest on VMware you need 64bit hardware and VT/AMD-V http://kb.vmware.com/selfservice/microsites/search.do?language=en_UScmd=displayKCexternalId=1003945 You got the point wrong, I'm talking running WITH 64 bit hardware in a 32 bit guest. This is done in Mac OS X Leopard (kernel is only 32 bit) and Mac OS X Snow Leopard (using 32 bit kernel not 64 bit one) by VMWare, Parallels and VirtualBox, as well as on Windows 32 bit using VMWare (dunno about VBox and Parallels, VirtualPC is unable to run 64 bit guests at all even on 64 bit hosts), just provided of course, the hardware is 64 bit. -- kvm to emulate 64 bit cpu on 32 bit host https://bugs.launchpad.net/bugs/596106 You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. Status in QEMU: Won't Fix Bug description: i wish kvm can run 64bit guest os on 32bit host just like qemu does.
