This proposal describes a method for translating any huge page address from virtual to physical or vice versa using simple addition or subtraction of a single fixed value. This allows devices to efficiently access arbitrary huge page memory, even stack data when worker stacks are in huge pages.
When legacy memory mode is used, it is possible to map a single virtual memory region large enough to cover all huge pages. During legacy hugepage init, each hugepage is mapped into that region. Once all pages have been mapped, any unused holes in that memory region are unmapped. This feature is applicable when rte_eal_iova_mode() == RTE_IOVA_PA and could be enabled either by default when the legacy memory EAL option is given, or a new EAL option could be added to specifically enable this feature. It may be desirable to set a capability bit when this feature is enabled to allow drivers to behave differently depending on the state of that flag. We have been working for some time with an internal patch that implements this functionality. While this patch works for us, it is not ready to be submitted upstream and we are open to suggested improvements. We would like to know whether this feature may be of interest to the wider DPDK community.
