On Fri, 2 May 2025 16:11:31 +0100 Bruce Richardson <bruce.richard...@intel.com> wrote:
> As the number of cores/cpus on platforms has increased over the years, > the use of coremasks rather than core-lists for identifying DPDK cores > has become more and more unwieldy. At this point, let's deprecate the > coremask-based EAL parameters for future removal, and point users to the > core-list based versions instead. > > Signed-off-by: Bruce Richardson <bruce.richard...@intel.com> Agree. There are some more syntax options on Linux kernel command line: https://github.com/torvalds/linux/blob/master/Documentation/admin-guide/kernel-parameters.rst#cpu-lists cpu lists Some kernel parameters take a list of CPUs as a value, e.g. isolcpus, nohz_full, irqaffinity, rcu_nocbs. The format of this list is: <cpu number>,...,<cpu number> or <cpu number>-<cpu number> (must be a positive range in ascending order) or a mixture <cpu number>,...,<cpu number>-<cpu number> Note that for the special case of a range one can split the range into equal sized groups and for each group use some amount from the beginning of that group: <cpu number>-<cpu number>:<used size>/<group size> For example one can add to the command line following parameter: isolcpus=1,2,10-20,100-2000:2/25 where the final item represents CPUs 100,101,125,126,150,151,... The value "N" can be used to represent the numerically last CPU on the system, i.e "foo_cpus=16-N" would be equivalent to "16-31" on a 32 core system. Keep in mind that "N" is dynamic, so if system changes cause the bitmap width to change, such as less cores in the CPU list, then N and any ranges using N will also change. Use the same on a small 4 core system, and "16-N" becomes "16-3" and now the same boot input will be flagged as invalid (start > end). The special case-tolerant group name "all" has a meaning of selecting all CPUs, so that "nohz_full=all" is the equivalent of "nohz_full=0-N". The semantics of "N" and "all" is supported on a level of bitmaps and holds for all users of bitmap_parselist().
