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Date:   Wed, 14 Feb 2018 09:54:25 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Lorenzo Colitti <lorenzo@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Mark D Rustad <mrustad@gmail.com>,
        Adam Borowski <kilobyte@angband.pl>,
        Joerg Roedel <jroedel@suse.de>,
        Andy Lutomirski <luto@kernel.org>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        "H . Peter Anvin" <hpa@zytor.com>, X86 ML <x86@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Juergen Gross <jgross@suse.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Borislav Petkov <bp@alien8.de>, Jiri Kosina <jkosina@suse.cz>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Brian Gerst <brgerst@gmail.com>,
        David Laight <David.Laight@aculab.com>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        Eduardo Valentin <eduval@amazon.com>,
        Will Deacon <will.deacon@arm.com>,
        "Liguori, Anthony" <aliguori@amazon.com>,
        Daniel Gruss <daniel.gruss@iaik.tugraz.at>,
        Hugh Dickins <hughd@google.com>,
        Kees Cook <keescook@google.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Waiman Long <llong@redhat.com>, Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH 00/31 v2] PTI support for x86_32
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On Tue, Feb 13, 2018 at 09:25:34AM -0800, Linus Torvalds wrote:
> On Tue, Feb 13, 2018 at 12:54 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> > On Sun, Feb 11, 2018 at 09:40:41AM -0800, Mark D Rustad wrote:
> >>
> >> ISTR that iscsi doesn't work when running a 64-bit kernel with a
> >> 32-bit userspace. I remember someone offered kernel patches to fix it,
> >> but I think they were rejected. I haven't messed with that stuff in
> >> many years, so perhaps the userspace side now has accommodation for
> >> it. It might be something to check on.
> >
> > IPSEC doesn't work with a 64bit kernel and 32bit userspace right now.
> >
> > Back in 2015 someone started to work on that, and properly marked that
> > the kernel could not handle this with commit 74005991b78a ("xfrm: Do not
> > parse 32bits compiled xfrm netlink msg on 64bits host")
> >
> > This is starting to be hit by some Android systems that are moving
> > (yeah, slowly) to 4.4 :(
> 
> Does anybody have test-programs/harnesses for this?

Lorenzo (now on the To: line), is the one that I think is looking into
this, and should have some sort of test for it.  Lorenzo?

> This is an area I care deeply about: I really want people to not have
> any excuses for not upgrading to a 64-bit kernel.  It used to be
> autofs (I actually added that whole "packetized pipe" model just to
> make automount "just w ork" even though the stupid protocol used a
> pipe to send command packets that had different layout on 32-bit and
> 64-bit).
> 
> See commit 64f371bc3107 ("autofs: make the autofsv5 packet file
> descriptor use a packetized pipe") for some discussion of that
> particular saga.
> 
> Some drm people used to run 32-bit kernels because of compat worries,
> and that would have been a disaster. They got very good about not
> having compat issues.
> 
> So let's try to fix the iscsi and ipsec issues. Not that anybody sane
> should use that overly complex ipsec thing, and I think we should
> strive to merge WireGuard and get people moved over to that instead,
> but I haven't heard anything from davem about it since I last asked..
> I have some hope that it's slowly happening.

WireGuard is still being worked on, it needs some crypto library changes
that should be coming soon, but will probably be 6 months out at the
earliest to get merged.  There are still lots of people using IPSEC :(

thanks,

greg k-h