mem: make base address hint OS specific

[dpdk.git] / lib / librte_eal / linux / eal / eal_memory.c

diff --git a/lib/librte_eal/linux/eal/eal_memory.c b/lib/librte_eal/linux/eal/eal_memory.c
index 226ac70..accfd2e 100644 (file)
--- a/lib/librte_eal/linux/eal/eal_memory.c
+++ b/lib/librte_eal/linux/eal/eal_memory.c
@@ -69,6 +69,26 @@ static int phys_addrs_available = -1;
 
 #define RANDOMIZE_VA_SPACE_FILE "/proc/sys/kernel/randomize_va_space"
 
+uint64_t eal_get_baseaddr(void)
+{
+       /*
+        * Linux kernel uses a really high address as starting address for
+        * serving mmaps calls. If there exists addressing limitations and IOVA
+        * mode is VA, this starting address is likely too high for those
+        * devices. However, it is possible to use a lower address in the
+        * process virtual address space as with 64 bits there is a lot of
+        * available space.
+        *
+        * Current known limitations are 39 or 40 bits. Setting the starting
+        * address at 4GB implies there are 508GB or 1020GB for mapping the
+        * available hugepages. This is likely enough for most systems, although
+        * a device with addressing limitations should call
+        * rte_mem_check_dma_mask for ensuring all memory is within supported
+        * range.
+        */
+       return 0x100000000ULL;
+}
+
 /*
  * Get physical address of any mapped virtual address in the current process.
  */