On Mon, 2 Jun 2025, Costa Shulyupin wrote:
> Writing values longer than 32 bits without a comma results in an error:
>
> echo 100000000 > /sys/kernel/debug/tracing/tracing_cpumask
> bash: echo: write error: Value too large for defined data type
>
> The bitmap_pars() kernel function specification:
> "Commas group hex digits into chunks.
> Each chunk defines exactly 32 bits of the resultant bitmask.
> No chunk may specify a value larger than 32 bits (%-EOVERFLOW)"
>
> Add a comma as a grouping separator every 32 bits to a hexadecimal number,
> as expected by the bitmap_pars() kernel function.
>
> Signed-off-by: Costa Shulyupin <costa.shul@xxxxxxxxxx>
>
> ---
> Cnahges in v2:
> - rebased
>
> Signed-off-by: Costa Shulyupin <costa.shul@xxxxxxxxxx>
> ---
> src/hwlatdetect/hwlatdetect.py | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/src/hwlatdetect/hwlatdetect.py b/src/hwlatdetect/hwlatdetect.py
> index dc28f38b751a..946bef33748b 100755
> --- a/src/hwlatdetect/hwlatdetect.py
> +++ b/src/hwlatdetect/hwlatdetect.py
> @@ -33,6 +33,11 @@ def info(istr):
> print(istr)
>
>
> +def group_sep(hex):
Can you rename the above since hex is a python built-in?
> + """ Add a comma as a grouping separator every 32 bits to a hexadecimal number. """
> + return ','.join([hex[max(i - 8, 0):i] for i in range(len(hex), 0, -8)][::-1])
> +
> +
> #
> # Class used to manage mounting and umounting the debugfs
> # filesystem. Note that if an instance of this class mounts
> @@ -494,7 +499,7 @@ def microseconds(sval):
> for i in range(l, r + 1):
> cpumask |= (1 << i)
> debug(f"set tracing_cpumask to {cpumask:x}")
> - detect.set("cpumask", f"{cpumask:x}")
> + detect.set("cpumask", group_sep(f"{cpumask:x}"))
>
> info(f"hwlatdetect: test duration {detect.testduration} seconds")
> info(f" detector: {detect.type}")
> --
> 2.48.1
>
>
>
