[PATCH] cmd: part: number: remove inconsistent 0x from returned value

[Stefan Herbrechtsmeier]

Hi,

Am 06.03.2021 um 21:12 schrieb Tom Rini:
> On Fri, Mar 05, 2021 at 07:35:24AM -0700, Simon Glass wrote:
>> Hi,
>>
>> On Fri, 5 Mar 2021 at 07:33, Stefan Herbrechtsmeier
>> <stefan.herbrechtsmeier-oss at weidmueller.com> wrote:
>>>
>>> Hi Eugeniu,
>>>
>>> Am 05.03.2021 um 12:52 schrieb Eugeniu Rosca:
>>>> Hello Stefan,
>>>>
>>>> On Fri, Mar 05, 2021 at 07:39:04AM +0000, Stefan Herbrechtsmeier wrote:
>>>>> From: Stefan Herbrechtsmeier <stefan.herbrechtsmeier at weidmueller.com>
>>>>>
>>>>> The part number sub-command returns the hexadecimal value with a leading
>>>>> 0x.
>>>>
>>>> That's to make sure that:
>>>>      - users have clear and unequivocal feedback that '10'
>>>>        returned by the command is really HEX 10, not DEC 10.
>>>>      - other U-Boot commands which need to take '0x10' as input
>>>>        will interpret it correctly, regardless of the way these
>>>>        other commands implement ascii-to-integer conversion.
>>>
>>> 'Almost all U-Boot commands expect numbers to be entered in hexadecimal
>>> input format.' [1]
>>>
>>> The filesystem commands use `simple_strtoul(.., 16)` and interpret the
>>> value as hexadecimal value.
>>>
>>> The 0x suggests that a 10 will be interpreted as decimal value and this
>>> isn't true.
>>>
>>>>> This is inconsistent with other values in the command
>>>>
>>>> It could be, but it is then better to fix the inconsistency in those
>>>> commands/sub-commands which add the ambiguity.
>>>
>>> Normally you are right but U-Boot by design use hexadecimal values
>>> without 0x. The env_set_hex functions doesn't use 0x.
>>>
>>>>> and U-Boot uses hexadecimal values generally.
>>>>
>>>> The key word is "generally", but not always. Some U-Boot commands will
>>>> process '10' as HEX 10 and some will process 10 as DEC 10. So, in order
>>>> to avoid these games, I vote for leaving the 0x in place.
>>
>> I would be very surprised if 10 means 0d10 in a partition number. I
>> agree that putting a 0x in these values is a dangerous precedent and
>> will just cause confusion. U-Boot uses hex for addresses and most
>> arguments
>>
>>>
>>> You can avoid it only if you could mark decimal numbers and that is
>>> impossible.
>>
>> 0d10 is available. People are not used to it though.
>>
>> Reviewed-by: Simon Glass <sjg at chromium.org>
>>
>>>
>>> @Tom: Does U-Boot still expect numbers to be hexadecimal values?
>>>
>>> [1] https://www.denx.de/wiki/DULG/UBootCommandLineInterface
>>>
>>>>>
>>>>> Signed-off-by: Stefan Herbrechtsmeier <stefan.herbrechtsmeier at weidmueller.com>
>>>>>
>>>>> ---
>>>>>
>>>>>    cmd/part.c | 2 +-
>>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/cmd/part.c b/cmd/part.c
>>>>> index 3395c17b89..56e1852c66 100644
>>>>> --- a/cmd/part.c
>>>>> +++ b/cmd/part.c
>>>>> @@ -152,7 +152,7 @@ static int do_part_info(int argc, char *const argv[], enum cmd_part_info param)
>>>>>               snprintf(buf, sizeof(buf), LBAF, info.size);
>>>>>               break;
>>>>>       case CMD_PART_INFO_NUMBER:
>>>>> -            snprintf(buf, sizeof(buf), "0x%x", part);
>>>>> +            snprintf(buf, sizeof(buf), "%x", part);
>>>>
> 
> I am not a fan of this change as well, especially having spent time on
> some platforms that have literally 20+ partition entries.  Being clear
> here that this is a hex value is important.

But isn't it confusing to use a 0x for a value which is treated as 
hexadecimal value by the commands independent of the 0x. The 0x results 
in the assumption that the partition is a decimal value without the 0x.

What is the correct way to convert a hexadecimal value into a decimal 
value on the shell? I need a value without prefix (decimal value) to 
pass it to the root parameter of the bootargs.

At the moment the different default numeral systems of common functions 
like load and test are very irritating. The load command uses 
hexadecimal value and doesn't support decimal value. The test command 
uses decimal value by default but supports hexadecimal values with a 
prefix. This means that the returned variable filesize of the command 
load couldn't be checked by test and the user have to use the itest command.

Regards
   Stefan