Re: [Xen-devel] [PATCH v2 03/17] tools/migration: Drop IHDR_VERSION constant from libxc and python

[Ian Jackson <ian.jackson@xxxxxxxxxx>]

Andrew Cooper writes ("Re: [PATCH v2 03/17] tools/migration: Drop IHDR_VERSION 
constant from libxc and python"):
> On 24/02/2020 17:25, Ian Jackson wrote:
> > Andrew Cooper writes ("[PATCH v2 03/17] tools/migration: Drop IHDR_VERSION 
> > constant from libxc and python"):
> >> Migration v3 is in the process of being introduced, meaning that the code 
> >> has
> >> to cope with both versions.  Use an explicit 2 for now.
> >>
> >> For the verify-stream-v2 and convert-legacy-stream scripts, update
> >> text to say "v2 (or later)".  What matters is the distinction vs
> >> legacy streams.
> > Can I request that you use a manifest constant for `2', rather than
> > sprinkling literal `2's everywhere ?  Something like IHDR_VERSION_2 ?
> > This may seem pointless, but it will mean that it is possible to grep
> > the code much more easily for things which are relevant to v2 or v3 or
> > whatever.
> >
> > (I don't it's necessary to go to any great lengths to substitute the
> > value of IHDR_VERSION_2 into error messages; a literal 2 in the string
> > is OK I think.)
> 
> As I reply previously... The value comes out of a pipe, and is checked
> exactly once.

I think we are talking at cross purposes.

I am suggesting that you replace every instance of a numeric literal
`2' in the code with IHDR_VERSION_2 (which would be a #define or enum
for 2).

I count 4 such literals.

> You can already grep for everything, using format_version which is where
> this number is stashed for the duration of restore.

None of the things I am talking about have "format_version" nearby.
They tend to have variants on "version" but that is a poor thing to
grep for.

Am I making any more sense now ?

Thanks,
Ian.

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