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mb/emulation/qemu-q35,qemu-i440fx: Add x86_64 support 

* Enable optional x86_64 romstage, postcar and ramstage
* Add Kconfig for x86_64 compilation
* Add documentation for x86 qemu mainboards
* Increase CAR stack as x86_64 uses more than 0x4000 bytes

Working:
* Boots to Linux
* Boots to SeaBIOS
* Drops to protected mode at end of ramstage
* Enumerates PCI devices
* Relocateable ramstage
* SMM

Change-Id: If2f02a95b2f91ab51043d4e81054354f4a6eb5d5
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/29667
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Patrick Rudolph 2018-11-15 13:42:15 +01:00 committed by Patrick Rudolph
parent e3dd57e106
commit 57907fcebf
5 changed files with 165 additions and 19 deletions
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29
Documentation/arch/x86/index.md
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@ -5,10 +5,11 @@ This section contains documentation about coreboot on x86 architecture.
* [x86 PAE support](pae.md)
## State of x86_64 support
At the moment there's no single board that supports x86_64 or to be exact
`ARCH_RAMSTAGE_X86_64` and `ARCH_ROMSTAGE_X86_64`.
At the moment there's only experimental x86_64 support.
The `emulation/qemu-i440fx` and `emulation/qemu-q35` boards do support
*ARCH_RAMSTAGE_X86_64* , *ARCH_POSTCAR_X86_64* and *ARCH_ROMSTAGE_X86_64*.
In order to add support for x86_64 the following assumptions are made:
In order to add support for x86_64 the following assumptions were made:
* The CPU supports long mode
* All memory returned by malloc must be below 4GiB in physical memory
* All code that is to be run must be below 4GiB in physical memory
@ -39,18 +40,16 @@ The page tables contains the following structure:
At the moment *$n* is 4, which results in identity mapping the lower 4 GiB.
## Steps to add basic support for x86_64
* Add x86_64 toolchain support - *DONE*
* Fix compilation errors - *DONE*
* Fix linker errors - *TODO*
* Add x86_64 rmodule support - *DONE*
* Add x86_64 exception handlers - *DONE*
* Setup page tables for long mode - *DONE*
* Add assembly code for long mode - *DONE*
* Add assembly code for SMM - *DONE*
* Add assembly code for postcar stage - *DONE*
* Add assembly code to return to protected mode - *DONE*
* Implement reference code for mainboard `emulation/qemu-q35` - *TODO*
## Basic x86_64 support
Basic support for x86_64 has been implemented for QEMU mainboard target.
## Reference implementation
The reference implementation is
* [QEMU i440fx](../../mainboard/emulation/qemu-i440fx.md)
* [QEMU Q35](../../mainboard/emulation/qemu-q35.md)
## TODO
* Identity map memory above 4GiB in ramstage
## Future work

64
Documentation/mainboard/emulation/qemu-i440fx.md Normal file
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@ -0,0 +1,64 @@
# qemu i440fx mainboard
## Running coreboot in qemu
Emulators like qemu don't need a firmware to do hardware init.
The hardware starts in the configured state already.
The coreboot port allows to test non mainboard specific code.
As you can easily attach a debugger, it's a good target for
experimental code.
## coreboot x86_64 support
coreboot historically runs in 32-bit protected mode, even though the
processor supports x86_64 instructions (long mode).
The qemu-i440fx mainboard has been ported to x86_64 and will serve as
reference platform to enable additional platforms.
To enable the support set the Kconfig option ``CONFIG_CPU_QEMU_X86_64=y``.
## Installing qemu
On debian you can install qemu by running:
```bash
$ sudo apt-get install qemu
```
On redhat you can install qemu by running:
```bash
$ sudo dnf install qemu
```
## Running coreboot
### To run the i386 version of coreboot (default)
Running on qemu-system-i386 will require a 32 bit operating system.
```bash
qemu-system-i386 -bios build/coreboot.rom -serial stdio -M pc
```
### To run the experimental x86_64 version of coreboot
Running on qemu-system-x86_64 allows to run a 32 bit or 64 bit operating system,
as well as firmware.
```bash
qemu-system-x86_64 -bios build/coreboot.rom -serial stdio -M pc
```
## Finding bugs
To test coreboot's x86 code it's recommended to run on a x86 host and enable KVM.
It will not only run faster, but is closer to real hardware. If you see the
following message:
KVM internal error. Suberror: 1
emulation failure
something went wrong. The same bug will likely cause a FAULT on real hardware,
too.
To enable KVM run:
```bash
qemu-system-x86_64 -bios build/coreboot.rom -serial stdio -M pc -accel kvm -cpu host
```

64
Documentation/mainboard/emulation/qemu-q35.md Normal file
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@ -0,0 +1,64 @@
# qemu q35 mainboard
## Running coreboot in qemu
Emulators like qemu don't need a firmware to do hardware init.
The hardware starts in the configured state already.
The coreboot port allows to test non mainboard specific code.
As you can easily attach a debugger, it's a good target for
experimental code.
## coreboot x86_64 support
coreboot historically runs in 32-bit protected mode, even though the
processor supports x86_64 instructions (long mode).
The qemu-q35 mainboard has been ported to x86_64 and will serve as
reference platform to enable additional platforms.
To enable the support set the Kconfig option ``CONFIG_CPU_QEMU_X86_64=y``.
## Installing qemu
On debian you can install qemu by running:
```bash
$ sudo apt-get install qemu
```
On redhat you can install qemu by running:
```bash
$ sudo dnf install qemu
```
## Running coreboot
### To run the i386 version of coreboot (default)
Running on qemu-system-i386 will require a 32 bit operating system.
```bash
qemu-system-i386 -bios build/coreboot.rom -serial stdio -M q35
```
### To run the experimental x86_64 version of coreboot
Running on `qemu-system-x86_64` allows to run a 32 bit or 64 bit operating system
and firmware.
```bash
qemu-system-x86_64 -bios build/coreboot.rom -serial stdio -M q35
```
## Finding bugs
To test coreboot's x86 code it's recommended to run on a x86 host and enable KVM.
It will not only run faster, but is closer to real hardware. If you see the
following message:
KVM internal error. Suberror: 1
emulation failure
something went wrong. The same bug will likely cause a FAULT on real hardware,
too.
To enable KVM run:
```bash
qemu-system-x86_64 -bios build/coreboot.rom -serial stdio -M q35 -accel kvm -cpu host
```

2
Documentation/mainboard/index.md
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@ -37,6 +37,8 @@ The boards in this section are not real mainboards, but emulators.
- [Spike RISC-V emulator](emulation/spike-riscv.md)
- [Qemu RISC-V emulator](emulation/qemu-riscv.md)
- [Qemu AArch64 emulator](emulation/qemu-aarch64.md)
- [Qemu x86 Q35](emulation/qemu-q35.md)
- [Qemu x86 PC](emulation/qemu-i440fx.md)
## Facebook

25
src/cpu/qemu-x86/Kconfig
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@ -2,12 +2,29 @@
config CPU_QEMU_X86
bool
select ARCH_BOOTBLOCK_X86_32
select ARCH_VERSTAGE_X86_32
select ARCH_ROMSTAGE_X86_32
select ARCH_RAMSTAGE_X86_32
select SMP
select UDELAY_TSC
select TSC_MONOTONIC_TIMER
select UNKNOWN_TSC_RATE
select SMM_ASEG
if CPU_QEMU_X86
config CPU_QEMU_X86_64
bool "Experimental 64bit support"
select ARCH_BOOTBLOCK_X86_64
select ARCH_VERSTAGE_X86_64
select ARCH_ROMSTAGE_X86_64
select ARCH_POSTCAR_X86_64
select ARCH_RAMSTAGE_X86_64
config CPU_QEMU_X86_32
bool
default n if CPU_QEMU_X86_64
default y
select ARCH_BOOTBLOCK_X86_32
select ARCH_VERSTAGE_X86_32
select ARCH_ROMSTAGE_X86_32
select ARCH_POSTCAR_X86_32
select ARCH_RAMSTAGE_X86_32
endif