Re: [PATCH 4/5] print: introduce a format specifier for pci_sbdf_t

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 24/05/2019 11:36, Jan Beulich wrote:
>>>> On 10.05.19 at 18:10, <roger.pau@citrix.com> wrote:
>> The new format specifier is '%pp', and prints a pci_sbdf_t using the
>> seg:bus:dev.func format. Replace all SBDFs printed using
>> '%04x:%02x:%02x.%u' to use the new format specifier.
> So on the positive side Linux doesn't use 'p' yet, so we're only at risk
> of a future conflict. However, having to pass a 64-bit pointer just
> to print a 32-bit entity seems rather wasteful to me. Since we can't
> use entirely new format specifiers, did you consider (ab)using one
> we rarely use, like %o, suffixed similarly like we do for %p? The
> extension could be restricted to apply only when neither field width
> nor precision nor any flags were specified, i.e. only to plain %o (at
> least initially).
>
> We'd then have something along the lines of
>
> #define PRI_sbdf "op"
> #define PRI_SBDF(v) ((v).sbdf)
>
> and
>
>     printk("%" PRI_sbdf ": ...\n", PRI_SBDF(pdev->sbdf), ...);

Except the answer will be the same as every time you've asked this in
the past.

No, because -Wformat doesn't tolerate it.

The *only* flexibility we have to play with is suffixes to %p

~Andrew

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