Re: [PATCH 4/4] x86/efi: print size and base in binary units in efi_print_memmap

From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Robert Elliott <elliott@hpe.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	"x86@kernel.org" <x86@kernel.org>,
	linux-efi@vger.kernel.org,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/4] x86/efi: print size and base in binary units in efi_print_memmap
Date: Sun, 27 Dec 2015 16:35:12 +0200	[thread overview]
Message-ID: <CAHp75VffR6FO=s5JeVPUPepVRyn-mwXF=juf+y1j44J69i3RKw@mail.gmail.com> (raw)
In-Reply-To: <20151221161629.GG4227@codeblueprint.co.uk>

On Mon, Dec 21, 2015 at 6:16 PM, Matt Fleming <matt@codeblueprint.co.uk> wrote:
> On Thu, 17 Dec, at 07:28:34PM, Robert Elliott wrote:
>> Print the base address for each range in decimal alongside the size.
>> Use a "(size @ base)" format similar to the fake_memmap kernel parameter.
>>
>> Print the range and base in the best-fit B, KiB, MiB, etc. units rather
>> than always MiB.  This avoids rounding, which can be misleading.
>>
>> Use proper IEC binary units (KiB, MiB, etc.) rather than misuse SI
>> decimal units (KB, MB, etc.).
>>
>> old:
>>     efi: mem61: [Persistent Memory  |   |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000880000000-0x0000000c7fffffff) (16384MB)
>>
>> new:
>>     efi: mem61: [Persistent Memory  |   |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000880000000-0x0000000c7fffffff] (16 GiB @ 34 GiB)
>>
>> Signed-off-by: Robert Elliott <elliott@hpe.com>
>> ---
>>  arch/x86/platform/efi/efi.c | 27 ++++++++++++++++++++++++---
>>  1 file changed, 24 insertions(+), 3 deletions(-)
>
> I'm not at all sure of the value of printing the physical address as a
> size. I would have thought that you'd have to convert it back to an
> address whenever you wanted to use it anyway.
>
>> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
>> index 635a955..030ba91 100644
>> --- a/arch/x86/platform/efi/efi.c
>> +++ b/arch/x86/platform/efi/efi.c
>> @@ -222,6 +222,25 @@ int __init efi_memblock_x86_reserve_range(void)
>>       return 0;
>>  }
>>
>> +char * __init efi_size_format(char *buf, size_t size, u64 bytes)
>> +{
>> +     if (!bytes || (bytes & 0x3ff))
>> +             snprintf(buf, size, "%llu B", bytes);
>> +     else if (bytes & 0xfffff)
>> +             snprintf(buf, size, "%llu KiB", bytes >> 10);
>> +     else if (bytes & 0x3fffffff)
>> +             snprintf(buf, size, "%llu MiB", bytes >> 20);
>> +     else if (bytes & 0xffffffffff)
>> +             snprintf(buf, size, "%llu GiB", bytes >> 30);
>> +     else if (bytes & 0x3ffffffffffff)
>> +             snprintf(buf, size, "%llu TiB", bytes >> 40);
>> +     else if (bytes & 0xfffffffffffffff)
>> +             snprintf(buf, size, "%llu PiB", bytes >> 50);
>> +     else
>> +             snprintf(buf, size, "%llu EiB", bytes >> 60);
>> +     return buf;

For me it looks like ffs with name in the table can be used.

>> +}
>> +
>
> Can we use string_get_size() instead of rolling our own function?
> --
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-- 
With Best Regards,
Andy Shevchenko