From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: buildroot@busybox.net
Subject: [Buildroot] [PATCH] arch/arm: add support for thumb(1) mode
Date: Wed, 17 Jul 2013 17:58:38 +0200 [thread overview]
Message-ID: <20130717175838.2fc2831e@skate> (raw)
In-Reply-To: <1374075555-9599-1-git-send-email-gustavo@zacarias.com.ar>
Dear Gustavo Zacarias,
On Wed, 17 Jul 2013 12:39:15 -0300, Gustavo Zacarias wrote:
> +config BR2_ARM_INSTRUCTIONS_THUMB
> + bool "Thumb"
> + depends on BR2_ARM_CPU_HAS_THUMB
> + help
> + This option instructions the compiler to generate Thumb
> + instructions, which allows to mix 16 bits instructions and
> + 32 bits instructions. This generally provides a much smaller
> + compiled binary size.
I think this is misleading: Thumb doesn't allow to mix 16 bits and 32
bits instructions like Thumb2 does. IIRC, with Thumb, a particular
function needs to be either completely Thumb (16 bits) or completely
ARM (32 bits), and there is the thumb-interworking mechanism between
the two.
Which leads me to this question: is adding Thumb support as simple as
what you're adding? Aren't there some additional thumb-interworking
complexities to handle?
Thanks!
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
next prev parent reply other threads:[~2013-07-17 15:58 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-17 15:39 [Buildroot] [PATCH] arch/arm: add support for thumb(1) mode Gustavo Zacarias
2013-07-17 15:58 ` Thomas Petazzoni [this message]
2013-07-17 16:03 ` Gustavo Zacarias
2013-07-17 19:58 ` Thomas Petazzoni
2013-07-17 22:25 ` Gustavo Zacarias
2013-07-18 7:19 ` Thomas Petazzoni
2013-07-18 11:08 ` Gustavo Zacarias
2013-07-18 11:24 ` Thomas Petazzoni
2013-07-18 8:10 ` Peter Korsgaard
2013-07-18 16:07 ` Gustavo Zacarias
2013-07-18 22:32 ` Peter Korsgaard
2013-07-18 22:46 ` Gustavo Zacarias
2013-07-19 8:19 ` Peter Korsgaard
2013-07-19 13:06 ` Gustavo Zacarias
2013-07-17 22:22 ` Peter Korsgaard
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