Do we need to support Thumb-2 code on ARMv6T2?
nicolas.pitre at linaro.org
Mon Mar 28 01:40:54 UTC 2011
On Sat, 26 Mar 2011, Tixy wrote:
> I.e. does CONFIG_THUMB2_KERNEL imply ARMv7 or newer?
> I assume this is the intent as arch/arm/Kconfig has
> depends on CPU_V7 && !CPU_V6 && !CPU_V6K && EXPERIMENTAL
> and there are no hits for the string "v6t" in the source tree
If you look at the log for commit 6e6fc998b8 which introduced that
dependency, you'll find:
|Author: Dave Martin <dave.martin at linaro.org>
|Date: Mon Dec 13 21:53:53 2010 +0100
| ARM: 6533/1: Thumb-2: Make CONFIG_THUMB2_KERNEL depend on !CPU_V6
| This makes sense, because Thumb-2 code can't execute on plain
| ARMv6 processors.
| This will avoid accidentally configuring a broken kernel where the
| config otherwise would allow multiple architecture versions to
| coexist in the same kernel.
| Not adding !CPU_V5 etc., because the chance of anyone trying to
| put v5 and v7 in the same kernel is low, and I'm not aware of
| any mach which can do this. These could be added later if it
| Note that the rules may need to be refined if support for the
| ARM1156J(F)-S processor is later added to the kernel, since this
| processor supports the rare ARMv6T2 extensions, which add support
| for Thumb-2 and a few other ARMv7 features.
| Signed-off-by: Dave Martin <dave.martin at linaro.org>
| Acked-by: Catalin Marinas <catalin.marinas at arm.com>
| Acked-by: Nicolas Pitre <nicolas.pitre at linaro.org>
| Acked-by: Santosh Shilimkar <santosh.shilimkar at ti.com>
| Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
So for now we don't support ARMv6T2. However this would still be a good
idea to add some comments next to the code that may rely on this
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