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U-booting Funtoo on the TI AM335x X2 SBC-B2
Introduction
Installing Funtoo to a Raspberry Pi is fun, but there are a lot more boards out there. For example, the carrier boards that hold a DIMM mounted AM335x series cpu. To get this going, we need to use the U-Boot bootloader, some knowledge of serial consoles, and a lot of patience.
When you pick a board, documentation is just as important as hardware features. Without it, you WILL be hunting down someone in Shenzhen to explain why the board refuses to boot (you forgot to ground C8, of course).
See http://funtoo.org/Crossdev_Automation for the xcompile_variables.sh script and environment variables referenced here, and a more complete introduction to the process via a complete install of Funtoo to Raspberry Pi 2 and 3.
U-Boot Building
root # wget $UBOOT_URL -O $UBOOTS/$UBOOT root # cd $UBOOTS root # mkdir u-boot && tar xf $UBOOT -C u-boot --strip-components 1 root # cd $XC_UBOOT root # ARCH=$ARCH CROSS_COMPILE=$CROSSDEV_TARGET- make mrproper root # ARCH=$ARCH CROSS_COMPILE=$CROSSDEV_TARGET- make distclean root # ARCH=$ARCH CROSS_COMPILE=$CROSSDEV_TARGET- make O=$XC_LINUX_PREFIX am335x_evm_config root # ARCH=$ARCH CROSS_COMPILE=$CROSSDEV_TARGET- make O=$XC_LINUX_PREFIX DTC=$XC_KERNEL_SRC/scripts/dtc/dtc
Kernel Building
Defconfig Generation
root # cd $XC_KERNEL_SRC root # ARCH=$ARCH CROSS_COMPILE=$CROSSDEV_TARGET ti_config_fragments/defconfig_builder.sh -t ti_sdk_am3x_release root # ARCH=$ARCH CROSS_COMPILE=$CROSSDEV_TARGET make ti_sdk_am3x_release_defconfig
root # ARCH=$ARCH CROSS_COMPILE=$CROSSDEV_TARGET- make uImage LOADADDR=0x82000000 root # ARCH=$ARCH CROSS_COMPILE=$CROSSDEV_TARGET- make modules root # ARCH=$ARCH CROSS_COMPILE=$CROSSDEV_TARGET- make am335x-evm.dtb am335x-evmsk.dtb am335x-bone.dtb am335x-boneblack.dtb am335x-bonegreen.dtb am335x-icev2.dtb
Setup Stage3
We set up the boot partion differently. The rest of the steps are the same.
root # sed -i "s/\/dev\/sda1.*/\/dev\/mmcblk0p1 \/boot/uboot vfat defaults 0 2/" $XC_STAGE3S/etc/fstab root # mkdir -p $XC_STAGE3S/boot/uboot
Copy Over Kernel Files
root # cd $XC_KERNEL_SRC root # ARCH=$ARCH CROSS_COMPILE=$CROSSDEV_TARGET- INSTALL_MOD_PATH=$XC_STAGE3S INSTALL_MOD_STRIP=1 make modules_install root # cp arch/arm/boot/zImage $XC_STAGE3S/boot root # cp arch/arm/boot/dts/*.dtb $XC_STAGE3S/boot root # get_kernel_release() { (cd $XC_KERNEL_SRC ; ARCH=$ARCH CROSS_COMPILE=$CROSSDEV_TARGET- make kernelrelease;) } root # rm $XC_STAGE3S/lib/modules/`get_kernel_release`/{build,source}
Copy Over U-Boot Files
Leave a blank line at the end. For some reason or other.
root # cp $XC_UBOOT/$XC_LINUX_PREFIX/{MLO,u-boot.img,u-boot.bin} $XC_STAGE3S/boot/uboot root # cp arch/arm/boot/uImage $XC_STAGE3S/boot/uboot root # echo "bootargs=console=ttyO0,115200n8 root=/dev/mmcblk0p2 mem=128M rootwait bootcmd=mmc rescan; fatload mmc 0 0x82000000 uImage; bootm 0x82000000 uenvcmd=boot " > $XC_STAGE3S/boot/uboot/uEnv.txt
Install to the Board
Make an image.
root # dd if=/dev/zero of=/dev/<your_dev> bs=1024 count=1024 root # parted -s /dev/<your_dev> mklabel msdos root # parted -s /dev/<your_dev> unit cyl mkpart primary fat32 -- 0 9 root # parted -s /dev/<your_dev> set 1 boot on root # parted -s /dev/<your_dev> unit cyl mkpart primary ext2 -- 9 -2
Mount and Copy
root # mkdir -p /mnt/funtoo root # mount /dev/<your_dev>2 /mnt/funtoo root # mkdir -p /mnt/funtoo/boot/uboot root # mount /dev/<your_dev>1 /mnt/funtoo/boot/uboot root # rsync -avz --exclude "usr/portage/*" $XC_STAGE3S/{boot,bin,etc,home,lib,mnt,opt,root,run,sbin,srv,tmp,usr,var,dev} /mnt/funtoo root # mkdir /mnt/funtoo/{proc,sys} root # umount -R /mnt/funtoo