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Date: Mon, 25 Aug 2014 17:49:17 +0300
From: Riku Voipio <riku.voipio@iki.fi>
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References: <20140825090917.GA14835@afflict.kos.to> <53FAFE92.9040001@suse.de>
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Subject: Re: [Qemu-devel] linux-user: enabling binfmt P flag
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To: Joakim Tjernlund <joakim.tjernlund@transmode.se>
Cc: peter.maydell@linaro.org, Riku Voipio <riku.voipio@iki.fi>, Alexander Graf <agraf@suse.de>, qemu-devel@nongnu.org

On Mon, Aug 25, 2014 at 04:30:40PM +0200, Joakim Tjernlund wrote:
> Riku Voipio <riku.voipio@iki.fi> wrote on 2014/08/25 15:55:55:
> > 
> > Hi,
> > 
> > On Mon, Aug 25, 2014 at 03:39:19PM +0200, Joakim Tjernlund wrote:
> > > Then consider when you run a LXC without P flag. 
> > 
> > Please remember that your usecase of running Qemu in LXC is a new 
> feature,
> > never before supported. Adding new features is always nice. However, it 
> must
> > not happen with expense of regressing already working features
> > (traditional chroot).
 
> OK, but traditional chroot is unaffected with my patch. Only binfmt
> users which uses the binfmt flag O will have to change to PO. How
> many is that? 

Traditional chroot is with binfmt_misc. Debian and ubuntu packages of
Qemu enable OC flags, so at least all debian/ubuntu users who use qemu
linux-user in chroots are affected. 

Using OC seems quite typical:

http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/app-emulation/qemu/files/qemu-binfmt.initd-r1?view=markup
http://rwmj.wordpress.com/2013/12/22/how-to-run-aarch64-binaries-on-an-x86-64-host-using-qemu-userspace-emulation/#content

Others, like Suse, scratchbox use the P flag and wrapper binary.