Re: [Xen-devel] [PATCH V2 6/6] iommu/arm: Add Renesas IPMMU-VMSA support

[Lars Kurth <lars.kurth@xxxxxxxxxx>]

On 07/08/2019, 20:15, "Julien Grall" <julien.grall@xxxxxxx> wrote:

    (+ Lars)
    
    Hi,
    
    On 8/7/19 5:01 PM, Oleksandr wrote:
    >>> + * you can found at:
    >>> + *    url: 
    >>> git://git.kernel.org/pub/scm/linux/kernel/git/horms/renesas-bsp.git
    >>> + *    branch: v4.14.75-ltsi/rcar-3.9.6
    >>> + *    commit: e206eb5b81a60e64c35fbc3a999b1a0db2b98044
    >>> + * and Xen's SMMU driver:
    >>> + *    xen/drivers/passthrough/arm/smmu.c
    >>> + *
    >>> + * Copyright (C) 2016-2019 EPAM Systems Inc.
    >>> + *
    >>> + * This program is free software; you can redistribute it and/or
    >>> + * modify it under the terms and conditions of the GNU General Public
    >>> + * License, version 2, as published by the Free Software Foundation.
    >>> + *
    >>> + * This program is distributed in the hope that it will be useful,
    >>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    >>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    >>> + * General Public License for more details.
    >>> + *
    >>> + * You should have received a copy of the GNU General Public
    >>> + * License along with this program; If not, see 
    >>> <http://www.gnu.org/licenses/>.
    >> I don't know that Xen license description rule, but since a few source 
    >> files have
    >> SPDX-License-Identifier, can we also use it on the driver?
    > 
    > I am afraid, I don't know a correct answer for this question. I would 
    > leave this to maintainers.
    > 
    > I just followed sample copyright notice for GPL v2 License according to 
    > the document:
    > 
    > http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=CONTRIBUTING
    
    The file CONTRIBUTING is only giving example of common example of 
    license. So I think this is fine to use SPDX, the more they are already 
    used. The only request is to put either SDPX or the full-blown text but 
    not the two :). Lars, any objection?
    
    I am quite in favor of SPDX because it is easier to find out the 
    license. With the full-blown text, the text may slightly vary between 
    licenses. For instance, the only difference between GPLv2 and GPLv2+ is 
    ",or (at your option) any later version". I let you imagine how it can 
    be easy to miss it when reviewing ;).
    
    We had a discussion last year about using SPDX in Xen code base but I 
    never got the time to formally suggest it.
    
I did not push it either. 

In the past one of the committers had major objections against SPDX, but after 
a conversation last year and changes to the latest version of SPDX he dropped 
these.

The only remaining objection was to have both SPDX identifier AND a license in 
the same file. The argument against it is: what does it mean if they contradict 
each other? To be fair that is a valid concern.

I am not sure it is a good idea to introduce SPDX piecemeal. It would be much 
better to
a) agree it
b) transform the codebase using a tool
rather than introducing it piecemeal

Lars
 

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