linux-kernel - Re: [PATCH v3 3/4] x86/efi: print size in binary units in efi_print

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Message-ID: <1453754667.2363.67.camel@HansenPartnership.com>
Date:	Mon, 25 Jan 2016 12:44:27 -0800
From:	James Bottomley <James.Bottomley@...senPartnership.com>
To:	Andy Shevchenko <andy.shevchenko@...il.com>
Cc:	"Elliott, Robert (Persistent Memory)" <elliott@....com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel @ vger . kernel . org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/4] x86/efi: print size in binary units in
 efi_print_memmap

On Mon, 2016-01-25 at 22:01 +0200, Andy Shevchenko wrote:
> On Mon, Jan 25, 2016 at 9:45 PM, James Bottomley
> <James.Bottomley@...senpartnership.com> wrote:
> > On Mon, 2016-01-25 at 21:28 +0200, Andy Shevchenko wrote:
> > > Also, in one version I tried to convert couple of other users
> > > which
> > > are using only KM (in general whatever range it would be) units.
> > > Any
> > > ideas how to modify to support them?
> > 
> > You mean units in odd increments of 6 digits (so K, M, T ...)? no. 
> >  The logarithmic reduction is done to the base of the unit 
> > increment (1000 or 1024) so it doesn't really fit this case and it 
> > would be hard to adjust because we don't have enough precision in 
> > the remainder.  However, unless there's a huge need to keep it, I'd 
> > just fit to the closest 3 digit increment and then everything would
> > work.
> 
> KM case:
> K) if 1 MiB > value >= 0 — prints in KiB
> M) if ∞ > value >= 1 MiB — prints in MiB.

Actually there is a way to do this: add a fixed precision argument that
would stop the logarithmic reduction when the desired precision were
reached.  You'd still have to do the precision discrimination in the
call, so something like

num > 1Mib ? call for precision of 6 : call for precision of 3

James