[PATCH 1/8] arm64: Import latest version of Cortex Strings' memcmp

[Mark Rutland]

On Wed, May 12, 2021 at 03:51:56PM +0100, Szabolcs Nagy wrote:
> The 05/12/2021 14:38, Robin Murphy wrote:
> > [ Dropping Kai Shen who is now bouncing, adding Szabolcs just in case ]
> > On 2021-05-12 14:28, Mark Rutland wrote:
> > > On Tue, May 11, 2021 at 05:12:31PM +0100, Robin Murphy wrote:
> > > > From: Sam Tebbs <sam.tebbs at arm.com>
> > > > 
> > > > Import the latest version of the former Cortex Strings - now
> > > > Arm Optimized Routines - memcmp function based on the upstream
> > > > code of string/aarch64/memcmp.S at commit e823e3a from
> > > > https://github.com/ARM-software/optimized-routines
> > > 
> > > What's the licensing/copyright situation here?
> > > 
> > > Because below...

> > > > --- a/arch/arm64/lib/memcmp.S
> > > > +++ b/arch/arm64/lib/memcmp.S
> > > > @@ -1,247 +1,139 @@
> > > >   /* SPDX-License-Identifier: GPL-2.0-only */
> > > 
> > > ... this says GPL-2.0-only ....
> > > 
> > > >   /*
> > > > - * Copyright (C) 2013 ARM Ltd.
> > > > - * Copyright (C) 2013 Linaro.
> > > > + * Copyright (c) 2013-2020, Arm Limited.
> > > >    *
> > > > - * This code is based on glibc cortex strings work originally authored by Linaro
> > > > - * be found @
> > > > - *
> > > > - * http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/
> > > > - * files/head:/src/aarch64/
> > > > + * Adapted from the original at:
> > > > + * https://github.com/ARM-software/optimized-routines/blob/master/string/aarch64/memcmp.S
> > > >    */
> > > 
> > > ... but this referenced file says "SPDX-License-Identifier: MIT", and I
> > > don't know when this relicensing is legitimate.
> > 
> > We were told that since the copyright was fully assigned back to Arm in the
> > move from Cortex Strings to Arm Optimized Routines, we are free to relicense
> > it as we see fit, so a GPLv2 submission to Linux was still fine.
> 
> yes, this code is fully owned by arm now, but the
> licensing is not clear to an outside observer.

Thanks for confirming!

It would be good if we could note this in the comment and/or the commit
message, since otherwise this isn't clear to said outside observers.

> arm optimized-routines uses MIT license since that
> seemed to be widely accepted, but then we were asked
> to contribute the code under BSD3, LLVM, GPLv2,...
> which is a bit of a pain (since then arm has to get
> involved, we wanted others to take the code without
> us having to do anything).

Sure, that makes sense.

My main concern here is that we have the right to relicense this as
GPLv2, since that avoids any pain points that come from mixed licensing.

Thanks,
Mark.