This RFC is a second, more complete, prototype of one approach we may want to take to help improve management of EAL cmdline arguments.
BACKGROUND: - The first problem that led to this work was that of providing a way for users to easily provide a set of CPU cores to DPDK where the CPU ids are >= RTE_MAX_LCORE - There are a number of solutions which were discussed for this, most of which involved automatically remapping CPU ids to lcore ids starting at zero. - However, in discussion with David M. at the last DPDK Summit in Prague, he pointed out the main difficulty with all these approaches in that they don't work with multi-process, since we can't reuse lcore id numbers in secondary process. - This in turn lead to a realisation that when processing cmdline arguments in DPDK, we always do so with very little context. So, for example, when processing the "-l" flag, we have no idea whether there will be later a --proc-type=secondary flag. We have all sorts of post-arg-processing checks in place to try and catch these scenarios. This patchset therefore tries to simplify the handling of argument processing, by explicitly doing an initial pass to collate all arguments into a structure. Thereafter, the actual arg parsing is done in a fixed order, meaning that e.g. when processing the --main-lcore flag, we have already processed the service core flags. We also can far quicker and easier check for conflicting options, since they can all be checked for NULL/non-NULL in the arg structure immediately after the struct has been populated. To do the initial argument gathering, this RFC uses the existing argparse library in DPDK. With recent changes, this now meets our needs for EAL argument parsing and allows us to not need to do direct getopt argument processing inside EAL at all. An additional benefit of this work, is that the argument parsing for EAL is much more centralised into common options. This reduces code a bit. However, what is missing here is proper handling for unsupported options across BSD and Windows. We can either take two approaches: 1. just ifdef them out so they don't appear in the argparse list on unsupported platforms, giving errors when used. 2. keep them in the list of arguments, and ignore them (with warning) when used on unsupported platforms. The advantage of #1 is that it is simple and correct, but the advantage of #2 is that is makes it easier to move scripts and commandline args between platforms - but at the cost of the arg list shown by help to be less accurate. Bruce Richardson (5): eal: add long options for each short option eal: define the EAL parameters in argparse format eal: gather EAL args before processing eal: combine parameter validation checks eal: simplify handling of conflicting cmdline options lib/eal/common/eal_common_memory.c | 3 +- lib/eal/common/eal_common_options.c | 1236 ++++++++++++++------------- lib/eal/common/eal_options.h | 101 +-- lib/eal/common/eal_private.h | 11 + lib/eal/freebsd/eal.c | 164 +--- lib/eal/linux/eal.c | 384 +-------- lib/eal/linux/eal_memory.c | 2 +- lib/eal/meson.build | 2 +- lib/eal/windows/eal.c | 113 +-- lib/meson.build | 1 + 10 files changed, 726 insertions(+), 1291 deletions(-) -- 2.48.1
