RE: [PATCH v3 1/2] vsprintf: Add %p[mM]U for uppercase MAC address

[David Laight <David.Laight@ACULAB.COM>]

From: Rasmus Villemoes
> Sent: 28 April 2023 07:57
> 
> On 27/04/2023 13.51, Konrad Gräfe wrote:
> > The CDC-ECM specification requires an USB gadget to send the host MAC
> > address as uppercase hex string. This change adds the appropriate
> > modifier.
> 
> Thinking more about it, I'm not sure this is appropriate, not for a
> single user like this. vsprintf() should not and cannot satisfy all
> possible string formatting requirements for the whole kernel. The %pX
> extensions are convenient for use with printk() and friends where one
> needs what in other languages would be "string interpolation" (because
> then the caller doesn't need to deal with temporary stack buffers and
> pass them as %s arguments), but for single items like this, snprintf()
> is not necessarily the right tool for the job.
> 
> In this case, the caller can just as well call string_upper() on the
> result, or not use sprintf() at all and do a tiny loop with
> hex_byte_pack_upper().

Or snprintf with "%02X:%02X:%02X:%02X:%02X:%02X".

	David

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