55 lines
2.0 KiB
Markdown
55 lines
2.0 KiB
Markdown
---
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title: Building Libreboot for Emulation
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x-toc-enable: true
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...
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Introduction
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============
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Libreboot supports building for qemu as a target board.
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The resulting rom can then be tested using qemu.
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The qemu board is mostly intended to speed up development by removing the need to flash to bare metal during initial tests.
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Qemu may also be useful for end users who intend to make changes to their libreboot rom without having to flash and reboot their machine.
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Building and Testing
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====================
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Libreboot can be built for qemu just like any other board.
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./build fw coreboot qemu_x86_12mb
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In order to test the resulting roms, you must have qemu installed on the host machine.
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Test the roms by pointing qemu to the rom in bios mode.
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For example:
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`qemu-system-x86_64 -bios bin/qemu_x86_12mb/grub_qemu_x86_12mb_libgfxinit_corebootfb_usqwerty_noblobs.rom`
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`qemu-system-x86_64 -bios bin/qemu_x86_12mb/uboot_payload_qemu_x86_12mb_libgfxinit_corebootfb_noblobs.rom -serial stdio`
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There is basic support for an arm64 virtual machine as well, although the payloads are not as developed as the x86 one:
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./build fw coreboot qemu_arm64_12mb
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```
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qemu-system-aarch64 -bios bin/qemu_arm64_12mb/uboot_payload_qemu_arm64_12mb_libgfxinit_corebootfb_noblobs.rom \
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-M virt,secure=on,virtualization=on,acpi=on -cpu cortex-a53 -m 768M -serial stdio -vga none -display none
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```
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NOTE: After the 20230625 release, U-Boot support was removed from x86 Qemu; it's
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also problematic on ARM-based Qemu. Only x86 qemu, with other payloads, is to
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be considered reliable for now.
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Use Cases
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=========
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While development is the primary motivation for qemu support, the board makes it easy to test minor changes to release roms.
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For example one can use *cbfstool* from coreboot to edit the background image in a libreboot rom as follows:
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```
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cbfstool /path/to/rom remove -n background.png
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cbfstool /path/to/rom add -f mynewbackground.png -n background.png -t raw
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```
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Using qemu allows the user to verify that the background image renders properly before performing the same operation on their release rom.
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