On Wed, Apr 16, 2025 at 02:44:55PM -0700, Andre Muezerie wrote: > DPDK uses GCC attribute "used" through macro __rte_used to indicate > that a variable not referenced in the code should be assumed being > used and therefore not be optimized away. This technique is used to embed > information in the binaries, by having crafted information stored in > them. > > MSVC offers similar functionality, but it differs significantly: MSVC > requires a pragma to be used to send a command to the linker telling it > explicitly the name of the symbol that should be included (even if not > referenced). As a side-effect, variables called out to be included cannot > be static, otherwise their symbols are not "seen" by the linker. This > restriction requires some DPDK code to be refactored. > > To assimilate these requirements/restrictions, macro RTE_INCLUDE is > introduced in this patch. > > Signed-off-by: Andre Muezerie <andre...@linux.microsoft.com> > --- > lib/eal/common/eal_common_options.c | 2 +- > lib/eal/include/rte_common.h | 6 ++++++ > 2 files changed, 7 insertions(+), 1 deletion(-) > > diff --git a/lib/eal/common/eal_common_options.c > b/lib/eal/common/eal_common_options.c > index b6fff7ec05..8d115a5bd7 100644 > --- a/lib/eal/common/eal_common_options.c > +++ b/lib/eal/common/eal_common_options.c > @@ -135,7 +135,7 @@ static const char *default_solib_dir = RTE_EAL_PMD_PATH; > * Note: PLEASE DO NOT ALTER THIS without making a corresponding > * change to usertools/dpdk-pmdinfo.py > */ > -static const char dpdk_solib_path[] __rte_used = > +RTE_INCLUDE(const char, dpdk_solib_path)[] = > "DPDK_PLUGIN_PATH=" RTE_EAL_PMD_PATH; > > TAILQ_HEAD(device_option_list, device_option); > diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h > index a6085dce27..4c5a3b668f 100644 > --- a/lib/eal/include/rte_common.h > +++ b/lib/eal/include/rte_common.h > @@ -231,6 +231,12 @@ typedef uint16_t unaligned_uint16_t; > /** > * Force symbol to be generated even if it appears to be unused. > */ > +#ifdef RTE_TOOLCHAIN_MSVC > +#define RTE_INCLUDE(type, name) __pragma(comment(linker, "/include:" > RTE_STR(name))) type name > +#else > +#define RTE_INCLUDE(type, name) __attribute__((used)) type name
Any reason we shouldn't also have "static" here, for the non-MSVC case? As a general question, is this needed for any/many tasks other than putting in place strings? Rather than having a general include macro, I'm just wondering if we are better doing specific macros for the driver string, and then other-string use-cases. /Bruce
