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Build kernel

Build kernel

Apr 21, 2020

 

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)

 

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

 

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