base: Add support for DT initrd/initramfs

Add a new API function, addBootData(), which allows the ports to specify
the size and load address of the initrd/initramfs via DeviceTree. This
uses the standard chosen nodes for initrd-start/initrd-end.

Update the addBootCmdline() to call addBootData() with no
initrd/initramfs so as to maintain backwards compatibility.

Change-Id: I7b1d5cf2a0b18685eaadf1d881434f3d48c45d8b
Signed-off-by: Alistair Delva <adelva@google.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/54183
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/base/loader/dtb_file.cc

@@ -63,12 +63,15 @@ DtbFile::~DtbFile()
 }
 
 bool
-DtbFile::addBootCmdLine(const char *_args, size_t len)
+DtbFile::addBootData(const char *_cmdline, size_t cmdline_len,
+                     off_t initrd_start, size_t initrd_len)
 {
     const char *root_path = "/";
     const char *node_name = "chosen";
     const char *full_path_node_name = "/chosen";
-    const char *property_name = "bootargs";
+    const char *bootargs_property_name = "bootargs";
+    const char *linux_initrd_start_property_name = "linux,initrd-start";
+    const char *linux_initrd_end_property_name = "linux,initrd-end";
 
     // Make a new buffer that has extra space to add nodes/properties
     int newLen = 2 * length;
@@ -102,8 +105,8 @@ DtbFile::addBootCmdLine(const char *_args, size_t len)
     }
 
     // Set the bootargs property in the /chosen node
-    ret = fdt_setprop((void *)fdt_buf_w_space, offset, property_name,
-                      (const void *)_args, len+1);
+    ret = fdt_setprop((void *)fdt_buf_w_space, offset, bootargs_property_name,
+                      (const void *)_cmdline, cmdline_len+1);
     if (ret < 0) {
         warn("Error setting \"bootargs\" property to flattened device tree, "
              "errno: %d\n", ret);
@@ -111,6 +114,30 @@ DtbFile::addBootCmdLine(const char *_args, size_t len)
         return false;
     }
 
+    if (initrd_len != 0) {
+        // Set the linux,initrd-start property in the /chosen node
+        ret = fdt_setprop_u64((void *)fdt_buf_w_space, offset,
+                              linux_initrd_start_property_name,
+                              (uint64_t)initrd_start);
+        if (ret < 0) {
+            warn("Error setting \"linux,initrd-start\" property to flattened "
+                 "device tree, errno: %d\n", ret);
+            delete [] fdt_buf_w_space;
+            return false;
+        }
+
+        // Set the computed linux,initrd-end property in the /chosen node
+        ret = fdt_setprop_u64((void *)fdt_buf_w_space, offset,
+                              linux_initrd_end_property_name,
+                              (uint64_t)initrd_start + initrd_len);
+        if (ret < 0) {
+            warn("Error setting \"linux,initrd-len\" property to flattened "
+                 "device tree, errno: %d\n", ret);
+            delete [] fdt_buf_w_space;
+            return false;
+        }
+    }
+
     // Repack the dtb for kernel use
     ret = fdt_pack((void *)fdt_buf_w_space);
     if (ret < 0) {

src/base/loader/dtb_file.hh

@@ -58,13 +58,27 @@ class DtbFile : public ImageFile
     DtbFile(const std::string &name);
     ~DtbFile();
 
+    /** Adds the passed in Command Line options and initrd for the kernel
+      * to the proper location in the device tree.
+      * @param _cmdline command line to append
+      * @param cmdline_len length of the command line string
+      * @param initrd_addr starting physical address of initrd
+      * @param initrd_len length of initrd data in memory
+      * @return returns true on success, false otherwise
+      */
+    bool addBootData(const char* _cmdline, size_t cmdline_len,
+                     off_t initrd_addr, size_t initrd_len);
+
     /** Adds the passed in Command Line options for the kernel
       * to the proper location in the device tree.
       * @param _args command line to append
       * @param len length of the command line string
       * @return returns true on success, false otherwise
       */
-    bool addBootCmdLine(const char* _args, size_t len);
+    inline bool
+    addBootCmdLine(const char* _args, size_t len) {
+        return addBootData(_args, len, 0, 0);
+    }
 
     /** Parse the DTB file enough to find the provided release
      * address and return it.