sys::memfd additional flags related to the hugetlb filesystem support. (#2252)

Author: devnexen

changelog/2252.added.md

@@ -0,0 +1 @@
+Added new `MemFdCreateFlag` constants to `sys::memfd` on Linux and Android related to hugetlbfs support.

src/sys/memfd.rs

@@ -29,6 +29,49 @@ libc_bitflags!(
         ///
         /// [`memfd_create(2)`]: https://man7.org/linux/man-pages/man2/memfd_create.2.html
         MFD_ALLOW_SEALING;
+        /// Anonymous file will be created using huge pages. It should be safe now to
+        /// combine with [`MFD_ALLOW_SEALING`] too.
+        /// However, despite its presence, on FreeBSD it is unimplemented for now (ENOSYS).
+        ///
+        /// See also the hugetlb filesystem in [`memfd_create(2)`].
+        ///
+        /// [`memfd_create(2)`]: https://man7.org/linux/man-pages/man2/memfd_create.2.html
+        #[cfg(linux_android)]
+        MFD_HUGETLB;
+        /// Following are to be used with [`MFD_HUGETLB`], indicating the desired hugetlb size.
+        ///
+        /// See also the hugetlb filesystem in [`memfd_create(2)`].
+        ///
+        /// [`memfd_create(2)`]: https://man7.org/linux/man-pages/man2/memfd_create.2.html
+        #[cfg(linux_android)]
+        MFD_HUGE_1MB;
+        /// hugetlb size of 2MB.
+        #[cfg(linux_android)]
+        MFD_HUGE_2MB;
+        /// hugetlb size of 8MB.
+        #[cfg(linux_android)]
+        MFD_HUGE_8MB;
+        /// hugetlb size of 16MB.
+        #[cfg(linux_android)]
+        MFD_HUGE_16MB;
+        /// hugetlb size of 32MB.
+        #[cfg(linux_android)]
+        MFD_HUGE_32MB;
+        /// hugetlb size of 256MB.
+        #[cfg(linux_android)]
+        MFD_HUGE_256MB;
+        /// hugetlb size of 512MB.
+        #[cfg(linux_android)]
+        MFD_HUGE_512MB;
+        /// hugetlb size of 1GB.
+        #[cfg(linux_android)]
+        MFD_HUGE_1GB;
+        /// hugetlb size of 2GB.
+        #[cfg(linux_android)]
+        MFD_HUGE_2GB;
+        /// hugetlb size of 16GB.
+        #[cfg(linux_android)]
+        MFD_HUGE_16GB;
     }
 );