From: Joel Stanley Date: Tue, 7 Jun 2022 03:20:03 +0000 (+0930) Subject: README: Add Linux on Microwatt instructions X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=9ec22af256ec1102dd34f8f23a38fbf71e5147f2;p=microwatt.git README: Add Linux on Microwatt instructions These instructions are similar to those at https://ozlabs.org/~joel/microwatt/README except they describe how to build the artifacts from scratch instead of downloading them. Signed-off-by: Joel Stanley --- diff --git a/README.md b/README.md index 63a93fe..7a00ca6 100644 --- a/README.md +++ b/README.md @@ -122,6 +122,68 @@ You should then be able to see output via the serial port of the board (/dev/tty fusesoc run --target=nexys_video microwatt ``` +## Linux on Microwatt + +Mainline Linux supports Microwatt as of v5.14. The Arty A7 is the best tested +platform, but it's also been tested on the OrangeCrab and ButterStick. + +1. Use buildroot to create a userspace + + A small change is required to glibc in order to support the VMX/AltiVec-less + Microwatt, as float128 support is mandiatory and for this in GCC requires + VSX/AltiVec. This change is included in Joel's buildroot fork, along with a + defconfig: + ``` + git clone -b microwatt https://github.com/shenki/buildroot + cd buildroot + make ppc64le_microwatt_defconfig + make + ``` + + The output is `output/images/rootfs.cpio`. + +2. Build the Linux kernel + ``` + git clone https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git + cd linux + make ARCH=powerpc microwatt_defconfig + make ARCH=powerpc CROSS_COMPILE=powerpc64le-linux-gnu- \ + CONFIG_INITRAMFS_SOURCE=/buildroot/output/images/rootfs.cpio -j`nproc` + ``` + + The output is `arch/powerpc/boot/dtbImage.microwatt.elf`. + +3. Build gateware using FuseSoC + + First configure FuseSoC as above. + ``` + fusesoc run --build --target=arty_a7-100 microwatt --no_bram --memory_size=0 + ``` + + The output is `build/microwatt_0/arty_a7-100-vivado/microwatt_0.bit`. + +4. Program the flash + + This operation will overwrite the contents of your flash. + + For the Arty A7 A100, set `FLASH_ADDRESS` to `0x400000` and pass `-f a100`. + + For the Arty A7 A35, set `FLASH_ADDRESS` to `0x300000` and pass `-f a35`. + ``` + microwatt/openocd/flash-arty -f a100 build/microwatt_0/arty_a7-100-vivado/microwatt_0.bit + microwatt/openocd/flash-arty -f a100 dtbImage.microwatt.elf -t bin -a $FLASH_ADDRESS + ``` + +5. Connect to the second USB TTY device exposed by the FPGA + + ``` + minicom -D /dev/ttyUSB1 + ``` + + The gateware has firmware that will look at `FLASH_ADDRESS` and attempt to + parse an ELF there, loading it to the address specified in the ELF header + and jumping to it. + ## Testing - A simple test suite containing random execution test cases and a couple of