This how-to describes the process of building the Linux kernel. This is a part of the Xilinx design flow described in Xilinx Open Source Linux.

Table of Contents

Task Dependencies (Pre-requisites)

Install Xilinx tools
Fetch Sources
Build Device Tree Compiler
Build U-Boot
Hardware Project (required for MicroBlaze only)

Tools Required

Cross-compilation toolchain (installed with Xilinx SDK)
system.mhs (from the hardware project) *required for MicroBlaze only

Environment Variables Required

"CROSS_COMPILE" for gcc cross platform compile settings
"PATH" for the make procedure being able to find the cross platform compiler tools
The settings of these environment variables can be found in Install Xilinx tools page

Input Files Required

Linux kernel source directory

Output Files Produced

Linux kernel images

Task Description

All commands need to be executed in the Linux kernel source directory.

Generic instructions for building the kernel

First, configure the Linux kernel:

make ARCH=<architecture> <kernel config>

Optionally, additional kernel options may be configured:

make ARCH=<architecture> (menu|x|n)config

Build the Linux kernel (requires that the environment is set up for cross compilation):

make ARCH=<architecture> UIMAGE_LOADADDR=<kernel load address> <make targets>

This will create the Linux images used for boot in linux-xlnx/arch/<architecture>/boot/, as well as linux-xlnx/vmlinux.

Linux for Zynq AP SoC

The kernel is configured based on linux-xlnx/arch/arm/configs/xilinx_zynq_defconfig:

make ARCH=arm xilinx_zynq_defconfig
make ARCH=arm menuconfig

To produce the kernel image:

make ARCH=arm UIMAGE_LOADADDR=0x8000 uImage

In the process, linux-xlnx/arch/arm/boot/Image and linux-xlnx/arch/arm/boot/zImage are created. The Image file is the uncompressed kernel image and the zImage file is a compressed kernel image which will uncompress itself when it starts.
If the mkimage utility is available in the build environment, linux-xlnx/arch/arm/boot/uImage will be created by wrapping zImage with a U-Boot header.

Linux for Zynq UltraScale+ MPSoC

The kernel is configured based on linux-xlnx/arch/arm64/configs/xilinx_zynqmp_defconfig:

make ARCH=arm64 xilinx_zynqmp_defconfig
make ARCH=arm64 menuconfig

To produce the kernel image:

make ARCH=arm64

In the process, linux-xlnx/arch/arm64/boot/Image is created. The Image file is the uncompressed kernel image.

Linux for MicroBlaze

The kernel is configured based on linux-xlnx/arch/microblaze/configs/mmu_defconfig:

make ARCH=microblaze mmu_defconfig

The kernel configuration needs to be modified to match the MicroBlaze settings as specified in <hardware project>/implementation/system.mhs:

make ARCH=microblaze menuconfig
   Platform options --->
      (<kernel load address>) Physical address where Linux Kernel is
      (1) USE_MSR_INSTR range (0:1)
      (1) USE_PCMP_INSTR range (0:1)
      (<0|1>) USE_BARREL range (0:1)
      (<0|1>) USE_DIV range (0:1)
      (<0|1|2>) USE_HW_MUL values (0=NONE, 1=MUL32, 2=MUL64)
      (<0|1|2>) USE_FPU values (0=NONE, 1=BASIC, 2=EXTENDED)
   Processor type and features --->
      [*] MMU support
      [ ] Default bootloader kernel arguments

The corresponding MicroBlaze entries in the system.mhs project file are:

BEGIN microblaze
   ...
   PARAMETER C_USE_BARREL = <0|1>
   PARAMETER C_USE_FPU = <0|1|2>
   PARAMETER C_USE_HW_MUL = <0|1|2>
   PARAMETER C_USE_DIV = <0|1>
   ...
END

<kernel load address> needs to be assigned to a valid address in memory as determined by the system.mhs project file. e.g.:

BEGIN axi_s6_ddrx
   ...
   C_S0_AXI_BASEADDR = <base address of memory>
   C_S0_AXI_HIGHADDR = <high address of memory>
   ...
END

To produce the arch/microblaze/boot/linux.bin kernel image:

make ARCH=microblaze UIMAGE_LOADADDR=<kernel load address> linux.bin

If the mkimage utility is available in the build environment, arch/microblaze/boot/linux.bin.ub will also be created. The *.ub suffix indicates that this file is linux.bin wrapped with the header required to boot Linux from U-Boot.

Linux for PowerPC

The kernel is configured based on linux-xlnx/arch/powerpc/44x/virtex5_defconfig:

make ARCH=powerpc 44x/virtex5_defconfig

make ARCH=powerpc menuconfig

To produce the kernel image:

make ARCH=powerpc UIMAGE_LOADADDR=0x8000 uImage

If the mkimage utility is available in the build environment, linux-xlnx/arch/microblaze/boot/uImage which is a U-Boot header.

Build Steps

Fetch Sources
Build FSBL
Build Device Tree Compiler (DTC)
Build PMU Firmware
Build Arm Trusted Firmware (ATF)
Build U-Boot
Build and Modify a Root File System
Build Device Tree Blob
(You are here) Build Linux Kernel
Prepare Boot Image
Prepare Boot Medium
Setup a Serial Console
Additional Information: Build Qt and Qwt Libraries

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