[PATCH v2 0/6] Enable setexpr command to print cpu-list like bitmaps

[Lukas Funke]

On 12.12.2023 12:40, Heinrich Schuchardt wrote:
> On 12.12.23 11:13, Heinrich Schuchardt wrote:
>> On 12.12.23 09:52, lukas.funke-oss at weidmueller.com wrote:
>>> From: Lukas Funke <lukas.funke at weidmueller.com>
>>>
>>>
>>> This series enables the 'setexpr' command to print "cpu list"-like
>>> bitmaps based on the printk format specifier [1].
>>>
>>> One use-case is to pass cpu list [2] based kernel parameter like
>>> 'isolcpu', 'nohz_full', irq affinity or RCU related CPU parameter to
>>> the kernel via a separate firmware variable without exposing the
>>> 'bootargs' variable to directly.
>>>
>>> Example:
>>>
>>> setexpr isolcpu_bootarg=%32pbl $myCPUisolation
>>
>> I applied your patches on top of origin/next but your example simply
>> does not work:
>>
>> => setenv myCPUisolation 123456789abcdef0
>> => setexpr isolcpu_bootarg=%32pbl $myCPUisolation
>> ## Error: illegal character '='in variable name "isolcpu_bootarg=%32pbl"
>>
>> This produces some output:
>>
>> => setexpr a fmt '%32pbl' 64; echo $a
>> 6
>>
>> But the result is completely unexpected. Number arguments in U-Boot are
>> always hexadecimal. So the output should be
>>
>> 2,5-6
> 
> doc/usage/cmd/setexpr.rst
> 
> has an example showing this.
> 
>      => setexpr foo fmt 0x%08x 63
>      => echo $foo
>      0x00000063
>      =>
> 
> You provide a use case for %pbl but not an reason why you want to
> support %pb. If you wanted to use the output in a device-tree
> manipulation the %pb output would have to be big-endian formatted.

I added it to be consistent with the kernel printk. Currently there is 
no use case for it. Shall we remove the %pb or leave it in for consistency?

Best regards
Lukas

> 
> Best regards
> 
> Heinrcih
> 
>>
>>> && env set bootargs "$isolcpu_bootarg"
>>> && bootm
>>>
>>> [1] https://www.kernel.org/doc/Documentation/printk-formats.txt
>>> [2]
>>> https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html
>>>
>>>
>>> Changes in v2:
>>> - Add bitmap format specifier to documentation
>>>
>>> Lukas Funke (6):
>>>    sandbox: add generic find_next_zero_bit implementation
>>>    linux: bitmap.h: add 'for_each_set_bitrange' iteration macro
>>>    test: cmd: setexptr: Add tests for bitmap string format
>>>    doc: printf() codes: Add bitmap format specifier
>>>    lib: vsprintf: enable '%*pb[l]' format specifier
>>>    cmd: printf: forward '%p' format string specifier
>>>
>>>   arch/sandbox/include/asm/bitops.h | 16 ++++++-
>>>   cmd/printf.c                      | 29 ++++++++++++
>>>   doc/develop/printf.rst            |  6 +++
>>>   include/linux/bitmap.h            |  7 +++
>>>   lib/vsprintf.c                    | 75 +++++++++++++++++++++++++++++++
>>>   test/cmd/setexpr.c                |  9 ++++
>>>   6 files changed, 140 insertions(+), 2 deletions(-)
>>>
>>
>