Boot Mode: DDR ELF Loading - Boot Mode: DDR ELF Loading - 2026.1 English - UG1186

How DDR Boot Works

The DDR boot process works as follows:

1. Linux remote processor (remoteproc) reads the ELF file from /lib/firmware/.
2. Specify the firmware name through sysfs: echo <elf name> > /sys/class/remoteproc/remoteproc0/firmware
3. The remoteproc driver opens and parses the ELF file.
4. The driver identifies the loadable segments (LOAD type) and the resource table section. It also reads virtual addresses (VA), physical addresses (PA), and sizes.
5. The driver maps ELF segment addresses to DDR and TCM memory regions.
   • .text (code), .data (initialized data), .bss (uninitialized data) sections
   • Segments are written to DDR starting at 0x9800100
   • Resource table is identified and tracked separately
6. The driver sets the R52 boot address to the ELF entry point and the control register to boot out of ELF-specified vector table location.
7. The driver releases the R52 core from reset.
   • EEMI calls to PMC power on R52 domain
   • TCMs are powered but not used for boot
   • R52 begins execution from DDR entry point

Zephyr Configuration for DDR Boot

1. Set the zephyr,sram property in the chosen node. This property tells the Zephyr build system where Linux loads the firmware.

   chosen {
       zephyr,sram = "/reserved-memory/ddrboot@9800100";
       /* ... */
   };

   This property affects:

   • Linker script generation: Zephyr's build system generates a linker script that places code/data at 0x9800100
   • Memory layout: Ensures all sections (.text, .data, .bss) fit within the 383 KB region
   • Resource table placement: Resource table is placed at a fixed offset that remoteproc can find
2. Review the linker script effect. When you set zephyr,sram = "/reserved-memory/ddrboot@9800100", the generated linker script includes memory placement like this:

   MEMORY
   {
       SRAM (wx) : ORIGIN = 0x09800100, LENGTH = 0x5ff00  /* 383 KB */
   }
   SECTIONS
   {
       .text : {
           *(.text*)
       } > SRAM
       .data : {
           *(.data*)
       } > SRAM
       .bss : {
           *(.bss*)
       } > SRAM
   }

3. Verify the build output. After you build the firmware, verify the ELF configuration.
   1. Check the ELF entry point.
   2. Check the program headers.

   # Check ELF entry point
   arm-none-eabi-readelf -h rpmsg_multi_services.elf | grep "Entry point"
   
   # Expected: Entry point address: 0x9800100
   
   # Check program headers
   arm-none-eabi-readelf -l rpmsg_multi_services.elf
   
   # Expected: LOAD segments starting at 0x09800100

4. Configure Linux remote processor DDR boot. The remoteproc driver selects DDR boot or TCM boot by checking the reserved memory node name in the device tree. The string ddrboot in the node name triggers ELFLOAD mode.
5. Define the reserved memory note. Use ddrboot in the reserved memory node name:

   reserved-memory {
       /* Node name must be "ddrboot" to trigger ELFLOAD */
       ddrboot_label: ddrboot@9800100 {
           phandle = <0x269>;
           device_type = "memory";
           no-map;
           reg = <0x0 0x9800100 0x0 0x5ff00>;  /* 383 KB */
       };
   };

6. Reference the DDR boot region in the remote processor node. Make sure that the memory-region property includes the ddrboot node:

   remoteproc@eba00000 {
       r52f@0 {
           compatible = "xlnx,versal2-r52f";
           memory-region = <&rsctbl9800000>,   /* Resource table */
                           <&vdev0buffer>,     /* Shared buffer */
                           <&vdev0vring0>,     /* TX vring */
                           <&vdev0vring1>,     /* RX vring */
                           <&ddrboot_label>;   /* DDR boot region */
           /* ... */
       };
   };

7. Follow the naming convention:
   • ddrboot@<address> triggers DDR boot or ELFLOAD.
   • tcm@<address> triggers TCM boot.