[Qemu-devel] [PATCH] add QEMU_LD_PREFIX environment variable

[josch <josch@pyneo.org>]

From: Johannes Schauer <j.schauer@email.de>

Hi,

qemu allows to specify the elf interpreter prefix with the -L option. When
using qemu user mode emulation through the binfmt mechanism, it is not
possible to pass any commandline arguments to qemu. Having qemu evaluate an
environment variable makes it possible to still supply a custom elf
interpreter prefix, even if qemu is executed by the binfmt mechanism.

My motivation is an emdebian project which creates foreign debian
bootstraps. Since foreign binaries are executed without an explicit
qemu-user call but by the binfmt mechanism, it relied on having appropriate
content in /etc/qemu-binfmt/$arch/ which is the default elf interpreter
prefix path on debian. The downside currently is, that the shared libraries
in /etc/qemu-binfmt/$arch/ have to be adapted very often for different
debian systems running on the same qemu $arch. This could be avoided by
setting the proposed environment variable QEMU_LD_PREFIX to the just
created debian rootfs. As mentioned earlier, the usage of the -L option
is not possible in this scenario because qemu-user is only implicitly
called by the binfmt mechanism.

Hopefully this change can be applied.

thanks!

cheers, josch

Johannes Schauer (1):
  add QEMU_LD_PREFIX environment variable

 linux-user/main.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

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1.7.5.4