mark is_hugetlbfs as Linux only

On Windows this function would always return None. There is no need to
make it OS-agnostic since it is only available on Linux.

Signed-off-by: Andreea Florescu <[email protected]>

Author: andreeaflorescu

src/guest_memory.rs

@@ -306,6 +306,7 @@ pub trait GuestMemoryRegion: Bytes<MemoryRegionAddress, E = Error> {
     /// assert_eq!(r.is_hugetlbfs(), None);
     /// # }
     /// ```
+    #[cfg(target_os = "linux")]
     fn is_hugetlbfs(&self) -> Option<bool> {
         None
     }
@@ -1221,6 +1222,7 @@ mod tests {
     }
 
     #[cfg(feature = "backend-mmap")]
+    #[cfg(target_os = "linux")]
     #[test]
     fn test_guest_memory_mmap_is_hugetlbfs() {
         let addr = GuestAddress(0x1000);

src/mmap.rs

@@ -457,6 +457,7 @@ impl GuestMemoryRegion for GuestRegionMmap {
         Ok(slice)
     }
 
+    #[cfg(target_os = "linux")]
     fn is_hugetlbfs(&self) -> Option<bool> {
         self.mapping.is_hugetlbfs()
     }

src/mmap_windows.rs

@@ -175,11 +175,6 @@ impl MmapRegion {
     pub fn file_offset(&self) -> Option<&FileOffset> {
         self.file_offset.as_ref()
     }
-
-    /// This information is not available on Windows platforms.
-    pub fn is_hugetlbfs(&self) -> Option<bool> {
-        None
-    }
 }
 
 impl AsSlice for MmapRegion {