From 1149b4fbb6002aa5a4cfe90bd404834721593968 Mon Sep 17 00:00:00 2001 From: Alejandro Hernandez Samaniego Date: Sun, 8 Jan 2023 12:15:23 -0700 Subject: baremetal-helloworld: Enable x86 and x86-64 ports - The qemux86 port for helloworld-baremetal builds in the standard way, however, it uses NASM syntax for the startup code, hence we include a dependency to nasm-native, QEMU forces us to use an ELF file rather than a bin file to boot from this architecture using the -kernel parameter. - QEMU refuses to boot using the -kernel parameter for files containing an ELF64 header [1], instead, it requires a multiboot2 compatible image. We could create an image that contains a multiboot2 header by piggybacking into grub2-native, specifically grub-mkrescue, but it requires some extra runtime dependencies (xorriso which is currently part of meta-oe), and assumes a grub installation exists on the host. Due to host contamination and dependency complications, we dont rely on grub2, but rather do this process manually instead, the x86-64 port contains a stage1 bootloader, stage2 bootloader and a 64 bit baremetal app (multiboot2 compatible), booting into real (16 bit), protected (32 bit) and long (64 bit) modes, eventually running the helloworld-baremetal app. This is the reason why we need the code changes to use a separate Makefile, and create an image specifically for qemux86-64. $ runqemu nographic Booting from ROM.. Hello OpenEmbedded on x86! $ runqemu nographic Starting Stage 1 Bootloader Loading Stage 2 Bootloader Stage 2 Loaded. Jumping to Stage2 Bootloader In Stage 2 Done Hello OpenEmbedded on x86-64! [1] https://gitlab.com/qemu-project/qemu/-/blob/v7.2.0/hw/i386/multiboot.c#L199 (From OE-Core rev: 1dffd81b2991f90ab95cb36d8ff7626efd21434f) Signed-off-by: Alejandro Enedino Hernandez Samaniego Signed-off-by: Alexandre Belloni Signed-off-by: Richard Purdie --- meta/classes-recipe/baremetal-image.bbclass | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'meta/classes-recipe') diff --git a/meta/classes-recipe/baremetal-image.bbclass b/meta/classes-recipe/baremetal-image.bbclass index 513155e9ae..70791f999a 100644 --- a/meta/classes-recipe/baremetal-image.bbclass +++ b/meta/classes-recipe/baremetal-image.bbclass @@ -86,6 +86,11 @@ QB_DEFAULT_FSTYPE ?= "bin" QB_DTB ?= "" QB_OPT_APPEND:append = " -nographic" +# QEMU x86 requires an .elf kernel to boot rather than a .bin +QB_DEFAULT_KERNEL:qemux86 ?= "${IMAGE_LINK_NAME}.elf" +# QEMU x86-64 refuses to boot from -kernel, needs a multiboot compatible image +QB_DEFAULT_FSTYPE:qemux86-64 ?= "iso" + # RISC-V tunes set the BIOS, unset, and instruct QEMU to # ignore the BIOS and boot from -kernel QB_DEFAULT_BIOS:qemuriscv64 = "" -- cgit v1.2.3-54-g00ecf