[Qemu-devel] qemu-ppc can't run static uClibc binaries.

[Rob Landley <rob@landley.net>]

Static binaries that run under the Linux kernel don't run under qemu-ppc.  For 
example, the prebuilt busybox binaries here:

  http://busybox.net/downloads/binaries/1.16.0/busybox-powerpc

Don't run under qemu-ppc, but runs just fine under qemu-system-ppc with the 
image at:

  http://impactlinux.com/fwl/downloads/binaries/system-image-powerpc.tar.bz2

The reason is that the "powerpc spec" that qemu was written to is for AIX, not 
for Linux, and thus the register layout qemu application emulation provides 
for powerpc doesn't match what the kernel is actually doing.

For dynamically linked executables, the dynamic linker reorganizes the 
register contents to match the AIX spec from IBM, but statically linked 
binaries get what the kernel provides directly.  Thus binaries statically 
linked against uClibc won't run under qemu-ppc, but run under qemu-system-ppc 
just fine.

I tracked down this problem in 2007:

  http://landley.net/notes-2007.html#28-03-2007

And reported it on the list at the time:

  http://lists.gnu.org/archive/html/qemu-devel/2007-03/msg00713.html
  http://lists.gnu.org/archive/html/qemu-devel/2007-03/msg00720.html
  http://lists.gnu.org/archive/html/qemu-devel/2007-04/msg00315.html

However, the then-maintainer of powerpc believed nobody else ever had the 
right to touch "her code":

  http://lists.gnu.org/archive/html/qemu-devel/2007-04/msg00198.html

And I was unable to convince her that insisting reality change to match a spec 
which wasn't even for the right platform was not a useful approach.  Thus the 
binary in the first link still won't run under qemu-ppc three years later, 
despite running fine under a real Linux kernel.

Rob
-- 
Latency is more important than throughput. It's that simple. - Linus Torvalds