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I'm on Ubuntu 12.04 for PowerPC and I installed Qemu just for kicks, having experience using it in the past to build an iso for an arm tablet, and upon doing a search I found this installed on my system:

/usr/bin/qemu-alpha
/usr/bin/qemu-arm
/usr/bin/qemu-armeb
/usr/bin/qemu-cris
/usr/bin/qemu-ga
/usr/bin/qemu-i386
/usr/bin/qemu-ifdown
/usr/bin/qemu-ifup
/usr/bin/qemu-img
/usr/bin/qemu-io
/usr/bin/qemu-launcher
/usr/bin/qemu-m68k
/usr/bin/qemu-microblaze
/usr/bin/qemu-mips
/usr/bin/qemu-mipsel
/usr/bin/qemu-nbd
/usr/bin/qemu-ppc
/usr/bin/qemu-ppc64
/usr/bin/qemu-ppc64abi32
/usr/bin/qemu-sh4
/usr/bin/qemu-sh4eb
/usr/bin/qemu-sparc
/usr/bin/qemu-sparc32plus
/usr/bin/qemu-sparc64
/usr/bin/qemu-system-arm
/usr/bin/qemu-system-cris
/usr/bin/qemu-system-i386
/usr/bin/qemu-system-m68k
/usr/bin/qemu-system-microblaze
/usr/bin/qemu-system-mips
/usr/bin/qemu-system-mips64
/usr/bin/qemu-system-mips64el
/usr/bin/qemu-system-mipsel
/usr/bin/qemu-system-ppc
/usr/bin/qemu-system-ppc64
/usr/bin/qemu-system-ppcemb
/usr/bin/qemu-system-sh4
/usr/bin/qemu-system-sh4eb
/usr/bin/qemu-system-sparc
/usr/bin/qemu-system-sparc64
/usr/bin/qemu-system-x86_64
/usr/bin/qemu-x86_64

But these can't all work for real can they? On PowerPC?

Sure they are installed but… what actually works?

Anyone know which architecture I would have fair success emulating with qemu on my PowerPC Ubuntu G4 Powerbook?

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2  
Why shouldn't they? They are probably very slow but it can work. –  Ulrich Dangel Apr 24 '13 at 13:51
    
Well, I'm interested in emulating Mac(ppc) or Windows(i386) or Android(arm) but I wonder which would perform the best. I assume PowerPC. –  Joshua Robison Apr 24 '13 at 23:34

1 Answer 1

up vote 1 down vote accepted

Sure they can (and do) work (QEMU stands for Q​uick EMU​lator), but will be much slower than their native couterparts - i.e. those that are using the same ISA (or a subset of it) as the real hardware - since much of the code can't be run directly (without emulation).

From my experience from about 3 years ago, QEMU-emulated PowerPC on x86 was one order of magnitude slower than the real thing (host running at 2.4GHz was 2-3 times slower than 600MHZ PPC).

This is also how one can for example test Android applications for ARM-based devices on *x86.

If you are interested in virtualising your actual hardware (i.e. you want to "emulate" the same architecture), you should get much closer to the actual performance - large portions of the code can be run natively and (optional) hardware support for virtualisation can extend this even more.

I've never clocked it myself and reports vary but I would expect to get to somewhere upwards of 90% native speed (on x86_64 I have seen claims about something like 2% overhead). A lot depends on what storage model you decide to use for your disk images - using a separate partition is of course faster than using a file, because you skip one additional layer - the file system (and with growing image format you are also losing on additional space allocations as the image grows). With plenty of RAM, putting the image into tmpfs is a speed boost you are unlikely to see on real hardware unless you tweak the system substantially (read close to booting - moving everything to tmpfs isn't that difficult).

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right but since I am on a PowerPC... wouldn't that somehow give me some kind of benefit in emulating PowerPC? –  Joshua Robison Apr 27 '13 at 23:28
    
Sure! - check the updated answer. I thought you were interested in the general cross-platform emulation. –  peterph Apr 29 '13 at 11:11

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