Re: [Xen-devel] [PATCH v2] build: specify minimum versions of make and binutils

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.01.16 at 14:02, <ian.campbell@xxxxxxxxxx> wrote:
> On Thu, 2016-01-28 at 05:49 -0700, Jan Beulich wrote:
>> > > > On 28.01.16 at 00:12, <cardoe@xxxxxxxxxx> wrote:
>> > To help people avoid having to figure out what versions of make and
>> > binutils need to be supported document them explicitly. The version of
>> > binutils that had to be supported was mentioned in
>> > http://lists.xenproject.org/archives/html/xen-devel/2016-01/msg00609.ht 
>> > ml 
>> > as 2.17 recently. It was decided that the versions should instead be
>> > GNU binutils 2.16.1 and GNU Make 3.80 in
>> > http://lists.xenproject.org/archives/html/xen-devel/2016-01/msg02134.ht 
>> > ml 
>> 
>> "decided" is a bit strong. I suggested these values. And while I'm
>> pretty certain that even plain make 3.80 will work, I'm in no way
>> sure plain 2.16.1 will (what I'm building with once in a while is some
>> 2.16.9x, and I can't say how many backports it has). So the
>> question really is - did you test that things build with these?
> 
> Why would he have done, you suggested 2.16.1 with no hint that you thought
> it might not be a reasonable version to use.
> 
> TBH having rejected Doug's original proposal I would have said it was up to
> you to specify the actual precise versions you think should be used, rather
> than making Doug guess and leading him down blind allies by making
> apparently authoritative suggestions which you secretly aren't actually
> sure about yourself.

To be honest it didn't even occur to me that someone might
propose such a patch without verifying things actually build
(unless using more cautious wording). Also note that in the first
reply to the v1 patch I did refer to 2.16.9x (which imo has made
clear that that's the lowest one I ever tested with recently), i.e.
I don't think I've actively mislead him.

> Anyway we could go round and round like this forever. What's wrong with
> starting with this as a baseline and bumping it if it turns out to be a
> problem in practice?

Well, we certainly could (which would be in line with my second
reply to v1), just that I'm not sure how much value such a doc
addition then has. At the very least it should then say "no
lower than 2.16.1, something slightly newer may be needed" or
some such.

>> Also I'm not sure 2.16.1 is going to be sufficient for ARM (it's
>> most definitely too old for ARM64).
> 
> I suppose there is an implicit max(version, first version supporting arch).
> I don't think we can really go into the level of detail needed for per arch
> toolchain requirements.

I'm afraid quite frequently "first version supporting arch" isn't
good enough. If we know otherwise for ARM64, that's certainly
fine.

> I certainly don't know which version of either gcc or binutils is needed to
> build either ARM variant.

Well, again - what's that documentation addition then good for?

Jan


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