diff options
| author | Ingo Molnar <mingo@kernel.org> | 2015-09-05 08:58:10 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-09-14 10:50:00 +0200 |
| commit | 1e6428124fe22906be0de1622c8fed8e50e5de05 (patch) | |
| tree | ad9771d7b2c225746bc9f9a5999fce65fe5520cd /arch/x86 | |
| parent | 7c5b190e115a2f7a51a85f261e7d7dca4b4bbe64 (diff) | |
| download | linux-1e6428124fe22906be0de1622c8fed8e50e5de05.tar.bz2 | |
x86/vm86: Fix the misleading CONFIG_VM86 Kconfig help text
The CONFIG_VM86 Kconfig help text is actively misleading, so fix it:
- Don't mark it 'obsolete' in the text as we'll support the ABI as long as CPUs
support it.
- Qualify the part about software emulation and mention that for some apps you
want a real vm86 mode.
- Don't scare users away from the option, instead explain what it does.
Reported-by: Stas Sergeev <stsp@list.ru>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Austin S Hemmelgarn <ahferroin7@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Josh Boyer <jwboyer@fedoraproject.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/Kconfig | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 48f7433dac6f..d28815325ef0 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1004,7 +1004,7 @@ config X86_THERMAL_VECTOR depends on X86_MCE_INTEL config X86_LEGACY_VM86 - bool "Legacy VM86 support (obsolete)" + bool "Legacy VM86 support" default n depends on X86_32 ---help--- @@ -1016,19 +1016,20 @@ config X86_LEGACY_VM86 available to accelerate real mode DOS programs. However, any recent version of DOSEMU, X, or vbetool should be fully functional even without kernel VM86 support, as they will all - fall back to (pretty well performing) software emulation. + fall back to software emulation. Nevertheless, if you are using + a 16-bit DOS program where 16-bit performance matters, vm86 + mode might be faster than emulation and you might want to + enable this option. - Anything that works on a 64-bit kernel is unlikely to need - this option, as 64-bit kernels don't, and can't, support V8086 - mode. This option is also unrelated to 16-bit protected mode - and is not needed to run most 16-bit programs under Wine. + Note that any app that works on a 64-bit kernel is unlikely to + need this option, as 64-bit kernels don't, and can't, support + V8086 mode. This option is also unrelated to 16-bit protected + mode and is not needed to run most 16-bit programs under Wine. - Enabling this option adds considerable attack surface to the - kernel and slows down system calls and exception handling. + Enabling this option increases the complexity of the kernel + and slows down exception handling a tiny bit. - Unless you use very old userspace or need the last drop of - performance in your real mode DOS games and can't use KVM, - say N here. + If unsure, say N here. config VM86 bool |