[U-Boot] [PATCH 1/1] arm: clean sizes.h

[Wolfgang Denk]

Dear Jean-Christophe PLAGNIOL-VILLARD,

In message <1241219918-22846-1-git-send-email-plagnioj at jcrosoft.com> you wrote:
> remove duplicated and clean it

Please just remove this. I mean, without attempting to clean it up.

[And not only on ARM, but everywhere.]


I never understood why "SZ_8K" would be better than 8192 or 8*1024 ?


Note that, apart from personal  preferences,  these  "helpful"  defi-
nitions are misleading and at least sometimes even plain wrong. See
below for details.

....
> --- a/include/asm-arm/sizes.h
> +++ b/include/asm-arm/sizes.h
> @@ -16,7 +16,7 @@
>  /* DO NOT EDIT!! - this file automatically generated
>   *                 from .s file by awk -f s2h.awk
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

It seems you ignore this warning? Is this a wise thing to do?

>  /* handy sizes */
> +#define SZ_16				0x00000010
> +#define SZ_256				0x00000100
> +#define SZ_512				0x00000200

NAK. I will not accept a patch that  adds  such  definitions.  That's
ridiculous.  What  is the problem of writing "16" when you mean "16"?
Why would "SZ_512" be any better than plain "512" - except that  it's
twice as much to type.


>  #define SZ_1K                           0x00000400
>  #define SZ_4K                           0x00001000
>  #define SZ_8K                           0x00002000

Please keep in mind that "K", "M", and "G" are non-standard prefixes,
and it is not clear if they refer to  decimal  or  binary  multiples.
This makes their use in the code a PITA.

We should try to be precise, and we should follow existing standards.

Prefixes and symbols for binary multiples  are  standardized  in  IEC
60027-2.  [They  are  not  part  of  the  SI  metric system of units,
though.] Correct names for 1024 = (1 << 10), 1024*1024 = ( 1  <<  20)
and 1024*1024*1024 = (1 << 30) are "kibi" (kilobinary, abbreviated as
"Ki"),  "mebi"  (megabinary,  "Mi"),  and  "gibi" (gigabinary, "Gi"),
respective. Note that this is "Ki", not "K".

So if you think youmust define something that means 8192, then please
name it "8 Ki", as "Ki" is the correct, standardized symbol  for  the
name "kibi", meaning "kilobinary".


With "8 K", nobody ever knows for sure what is meant - is it 8*10**3
or is it 8*2**10.

Thus my urgent recommendation: let's get rid of  all  this  ambiguous
SZ_*  definitions and use numbers. "8 * 1024" is at least as readable
as "SZ_8K", and it leaves no doubt what might be meant.


Thanks.


Best regards,

Wolfgang Denk

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