65 lines
1.7 KiB
Markdown
65 lines
1.7 KiB
Markdown
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# qemu q35 mainboard
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## Running coreboot in qemu
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Emulators like qemu don't need a firmware to do hardware init.
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The hardware starts in the configured state already.
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The coreboot port allows to test non mainboard specific code.
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As you can easily attach a debugger, it's a good target for
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experimental code.
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## coreboot x86_64 support
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coreboot historically runs in 32-bit protected mode, even though the
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processor supports x86_64 instructions (long mode).
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The qemu-q35 mainboard has been ported to x86_64 and will serve as
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reference platform to enable additional platforms.
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To enable the support set the Kconfig option ``CONFIG_CPU_QEMU_X86_64=y``.
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## Installing qemu
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On debian you can install qemu by running:
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```bash
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$ sudo apt-get install qemu
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```
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On redhat you can install qemu by running:
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```bash
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$ sudo dnf install qemu
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```
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## Running coreboot
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### To run the i386 version of coreboot (default)
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Running on qemu-system-i386 will require a 32 bit operating system.
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```bash
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qemu-system-i386 -bios build/coreboot.rom -serial stdio -M q35
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```
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### To run the experimental x86_64 version of coreboot
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Running on `qemu-system-x86_64` allows to run a 32 bit or 64 bit operating system
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and firmware.
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```bash
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qemu-system-x86_64 -bios build/coreboot.rom -serial stdio -M q35
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```
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## Finding bugs
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To test coreboot's x86 code it's recommended to run on a x86 host and enable KVM.
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It will not only run faster, but is closer to real hardware. If you see the
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following message:
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KVM internal error. Suberror: 1
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emulation failure
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something went wrong. The same bug will likely cause a FAULT on real hardware,
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too.
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To enable KVM run:
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```bash
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qemu-system-x86_64 -bios build/coreboot.rom -serial stdio -M q35 -accel kvm -cpu host
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```
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