linux-kernel - Re: [PATCH 14/14] x86/efi: Print size in binary units in efi_print

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Date:	Tue, 9 Feb 2016 13:20:18 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	"Elliott, Robert (Persistent Memory)" <elliott@....com>
Cc:	Matt Fleming <matt@...eblueprint.co.uk>,
	Laszlo Ersek <lersek@...hat.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Taku Izumi <izumi.taku@...fujitsu.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 14/14] x86/efi: Print size in binary units in
 efi_print_memmap


* Elliott, Robert (Persistent Memory) <elliott@....com> wrote:

> 
> > -----Original Message-----
> > From: Matt Fleming [mailto:matt@...eblueprint.co.uk]
> > Sent: Wednesday, February 3, 2016 5:28 AM
> > To: Ingo Molnar <mingo@...nel.org>
> > Cc: Laszlo Ersek <lersek@...hat.com>; H . Peter Anvin <hpa@...or.com>;
> > Thomas Gleixner <tglx@...utronix.de>; linux-efi@...r.kernel.org; linux-
> > kernel@...r.kernel.org; Elliott, Robert (Persistent Memory)
> > <elliott@....com>; Andy Shevchenko <andriy.shevchenko@...ux.intel.com>;
> > Ard Biesheuvel <ard.biesheuvel@...aro.org>; Taku Izumi
> > <izumi.taku@...fujitsu.com>; Linus Torvalds <torvalds@...ux-
> > foundation.org>; Andrew Morton <akpm@...ux-foundation.org>
> > Subject: Re: [PATCH 14/14] x86/efi: Print size in binary units in
> > efi_print_memmap
> ...
> > OK, this patch has caused enough headaches. Let's drop it from this
> > series.
> > 
> > Robert, Andy, feel free to resubmit it after you've addressed
> > everyone's concerns and we can discuss it in isolation.
> 
> We could just delete the size print altogether - better to print
> nothing than a silently rounded number.  The end address already
> communicates the size - it's just not as readable.  
> 
> The e820 table prints don't bother with a size print. 
> 
> That would also shorten these extremely wide prints to 116
> characters (131 if printk time is enabled).
> 
> [    0.000000] BIOS-e820: [mem 0x0000001880000000-0x000000207fffffff] reserved
> vs.
> [    0.000000] efi: mem62: [Reserved           |   |  |NV|  |  |  |  |   |WB|WT|WC|UC] range=[0x0000001880000000-0x000000207fffffff] (32 GiB)

So I find the latter a lot more readable - my terminals are wide enough ;-)

Humans are also rather bad at parsing 64-bit hexa address ranges at a glance, so 
the size display is very useful.

But the flags portion should be shortened via appropriately chosen 
single-character abbreviations for the flags. Anyone deeply intimate with the code 
will recognize the flags - others won't care one way or another.

plus there's no need to write out 'range='.
  
... and please keep the size and just use GB/TB for chrissake.

I.e. something like this would work for me:

> [    0.000000] efi: mem62: 0x0000001880000000-0x000000207fffffff (  32 GB) .N....BTCU "Reserved"

Thanks,

	Ingo