[coreboot] [commit] r5072 - trunk/src/devices
svn at coreboot.org
Sun Jan 31 22:46:12 CET 2010
Date: Sun Jan 31 22:46:12 2010
New Revision: 5072
- Improve help texts for option ROM initialization methods
- disallow REAL_MODE method if ARCH_X86 is not set.
Signed-off-by: Stefan Reinauer <stepan at coresystems.de>
Acked-by: Stefan Reinauer <stepan at coresystems.de>
--- trunk/src/devices/Kconfig Sun Jan 31 21:51:00 2010 (r5071)
+++ trunk/src/devices/Kconfig Sun Jan 31 22:46:12 2010 (r5072)
@@ -42,32 +42,50 @@
Examples include IDE/SATA controller option ROMs and option ROMs
for network cards (NICs).
-# TODO: Describe YABEL vs. x86emu differences in more detail.
prompt "Option ROM execution type"
- default PCI_OPTION_ROM_RUN_REALMODE
+ default PCI_OPTION_ROM_RUN_YABEL if !ARCH_X86
+ default PCI_OPTION_ROM_RUN_REALMODE if ARCH_X86
depends on PCI_ROM_RUN || VGA_ROM_RUN
prompt "Real mode"
+ depends on ARCH_X86
If you select this option, PCI option ROMs will be executed
- natively on the hardware (a 32bit x86 system is required).
+ natively on the CPU in real mode. No CPU emulation is involved,
+ so this is the fastest, but also the least secure option.
+ (only works on x86/x64 systems)
- prompt "YABEL"
+ prompt "x86emu"
- If you select this option, the YABEL BIOS emulator will be used to
- execute PCI option ROMs.
+ If you select this option, the x86emu CPU emulator will be used to
+ execute PCI option ROMs.
+ When choosing this option, x86emu will pass through all hardware
+ accesses to memory and IO devices to the underlying memory and IO
+ addresses. While this option prevents option ROMs from doing dirty
+ tricks with the CPU (such as installing SMM modules or hypervisors),
+ they can still access all devices in the system.
+ Choosing x86emu, option ROM execution is slower than native execution
+ in real mode, but faster than the full system emulation YABEL
+ This is the default choice for non-x86 systems.
- prompt "x86emu"
+ prompt "YABEL"
- If you select this option, the x86emu BIOS emulator will be used to
+ If you select this option, the YABEL system emulator will be used to
execute PCI option ROMs.
+ YABEL consists of two parts: It uses x86emu for the CPU emulation and
+ additionally provides a PC system emulation that filters bad device and
+ memory access (such as PCI config space access to other devices than the
+ initialized one).
+ This option best prevents option ROMs from doing dirty tricks with the
+ system (such as installing SMM modules or hypervisors), but it is also
+ significantly slower than the other option ROM initialization methods.
More information about the coreboot