On Linux, xrt-runner should use MAP_SHARED for readonly memory mapped… (Xilinx#9838)

* On Linux, xrt-runner should use MAP_SHARED for readonly memory mapped artifcats or else amdxdna returns EFAULT error code when creating BO

Signed-off-by: Sonal Santan <sonal.santan@amd.com>

* Improve userptr details in xrt::bo inline documentation

Signed-off-by: Sonal Santan <sonal.santan@amd.com>

---------

Signed-off-by: Sonal Santan <sonal.santan@amd.com>

Author: sonals

src/runtime_src/core/common/runner/detail/linux/mmap.h

@@ -97,7 +97,7 @@ struct mmap_artifact
   static void*
   map_region(int fd, std::size_t size)
   {
-    void* ptr = mmap(nullptr, size, PROT_READ, MAP_PRIVATE, fd, 0);
+    void* ptr = mmap(nullptr, size, PROT_READ, MAP_SHARED, fd, 0);
     if (ptr == MAP_FAILED)
     {
       close(fd);

src/runtime_src/core/include/xrt/xrt_bo.h

@@ -160,7 +160,10 @@ class bo
    * @param device
    *  The device on which to allocate this buffer
    * @param userptr
-   *  Pointer to aligned user memory
+   *  Pointer to 4K aligned user memory allocated using OS provided aligned
+   *  allocator.
+   *  A readonly pointer may be obtained via a readonly mmap of a file
+   *  opened in readonly mode.
    * @param sz
    *  Size of buffer
    * @param flags
@@ -181,7 +184,10 @@ class bo
    * @param device
    *  The device on which to allocate this buffer
    * @param userptr
-   *  Pointer to aligned user memory
+   *  Pointer to 4K aligned user memory allocated using OS provided aligned
+   *  allocator.
+   *  A readonly pointer may be obtained via a readonly mmap of a file
+   *  opened in readonly mode.
    * @param sz
    *  Size of buffer
    * @param grp
@@ -272,7 +278,10 @@ class bo
    * @param hwctx
    *  The hardware context in which to allocate this buffer
    * @param userptr
-   *  Pointer to aligned user memory
+   *  Pointer to 4K aligned user memory allocated using OS provided aligned
+   *  allocator.
+   *  A readonly pointer may be obtained via a readonly mmap of
+   *  a file opened in readonly mode.
    * @param sz
    *  Size of buffer
    * @param flags
@@ -293,7 +302,10 @@ class bo
    * @param hwctx
    *  The hardware context in which to allocate this buffer
    * @param userptr
-   *  Pointer to aligned user memory
+   *  Pointer to 4K aligned user memory allocated using OS provided aligned
+   *  allocator.
+   *  A readonly pointer may be obtained via a readonly mmap of a file
+   *  opened in readonly mode.
    * @param sz
    *  Size of buffer
    * @param grp