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UEFI platforms with a Devicetree have recently gained support for some form of network booting. [1][2] On those platforms, the UEFI firmware downloads the disk image over the network and presents it to UEFI applications using the simple filesystem protocol. This is sufficient for OS loaders such as e.g. GRUB to find their configuration and load the kernel image. The firmware must also describe the ramdisk to the OS, so that it finds its root filesystem. On ACPI based platforms this is done with an NVDIMM Firmware Interface Table (NFIT). On Devicetree based platforms, this can be done with a pmem node. [3] Add a kernel config fragment to add pmem support, which enables network boot on UEFI platforms with Devicetree. Also, briefly mention that we support this scenario in the readme. This can be tested on Qemu, with the following procedure: Build aarch64_efi_defconfig in a folder, to obtain output/images/disk.img, and serve the image over HTTP with python: $ python -m http.server -d output/images/ In another terminal and another folder, configure a U-Boot based firmware starting from qemu_aarch64_ebbr_defconfig, and with the following additional configurations: BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2026.04" BR2_TARGET_UBOOT_NEEDS_DTC=y Add the following U-Boot configurations to board/qemu/aarch64-ebbr/u-boot.fragment: CONFIG_EFI_HTTP_BOOT=y CONFIG_NET_LWIP=y Build everything; you should obtain output/images/flash.bin. Start Qemu as per board/qemu/aarch64-ebbr/readme.txt, but omitting the hd0 -device and -drive stanzas. U-Boot should start; interrupt it with enter. At U-Boot prompt, type the following commands: => setenv loadaddr 0x43000000 => efidebug boot rm 0 => efidebug boot add -u 0 net http://10.0.2.2:8000/disk.img => efidebug boot order 0 => bootefi bootmgr U-Boot should download the disk image over HTTP and boot Linux with UEFI. Look for the following message in Linux boot log, to confirm that it did indeed mount its rootfs from the downloaded image: EXT4-fs (pmem0p2): mounted filesystem ... Link: https://www.linaro.org/blog/installing-fedora-with-uefi-http-boot/ [1] Link: https://docs.u-boot-project.org/en/latest/develop/uefi/uefi.html#uefi-http-boot-using-the-legacy-tcp-stack [2] Link: https://github.com/ARM-software/edge-iot-arch-guide/blob/main/source/http-boot/pmem_node.md [3] Signed-off-by: Vincent Stehlé <vincent.stehle@arm.com> Cc: Dick Olsson <hi@senzilla.io> Signed-off-by: Julien Olivain <ju.o@free.fr>
Buildroot is a simple, efficient and easy-to-use tool to generate embedded Linux systems through cross-compilation. The documentation can be found in docs/manual. You can generate a text document with 'make manual-text' and read output/docs/manual/manual.text. Online documentation can be found at https://buildroot.org/docs.html To build and use the buildroot stuff, do the following: 1) run 'make menuconfig' 2) select the target architecture and the packages you wish to compile 3) run 'make' 4) wait while it compiles 5) find the kernel, bootloader, root filesystem, etc. in output/images You do not need to be root to build or run buildroot. Have fun! Buildroot comes with a basic configuration for a number of boards. Run 'make list-defconfigs' to view the list of provided configurations. Please feed suggestions, bug reports, insults, and bribes back to the buildroot mailing list: buildroot@buildroot.org You can also find us on #buildroot on OFTC IRC. If you would like to contribute patches, please read https://buildroot.org/manual.html#submitting-patches