From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoffer Dall <christoffer.dall@linaro.org>
Date: Tue, 30 Jul 2013 07:31:41 -0700
Subject: [U-Boot] [PATCH v3 6/7] ARM: extend non-secure switch to also
 go into HYP mode
In-Reply-To: <51F7AAA1.3030409@linaro.org>
References: <1373414059-22779-1-git-send-email-andre.przywara@linaro.org>
	<1373414059-22779-7-git-send-email-andre.przywara@linaro.org>
	<20130729220246.GD26768@cbox> <51F7AAA1.3030409@linaro.org>
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On Tue, Jul 30, 2013 at 01:59:29PM +0200, Andre Przywara wrote:
> On 07/30/2013 12:02 AM, Christoffer Dall wrote:
> >On Wed, Jul 10, 2013 at 01:54:18AM +0200, Andre Przywara wrote:

[...]

> >>
> >>+_hyp_trap:
> >>+	mrs	lr, elr_hyp	@ for older asm: .byte 0x00, 0xe3, 0x0e, 0xe1
> >
> >this comment just confuses: either make it intelligent to support an
> >older compiler or just get rid of these byte encodings.  You can always
> >disassemble the file and lookup the byte code with a modern compiler to
> >get back to the byte encoding.
> 
> Well, I used a Debian 6 cross compiler before, which didn't support
> these instructions. After your remark I updated the system to Debian
> 7, but found it not appropriate to ask any user to do the same just
> to use a fixed, non-parametrized assembly instruction. I have the
> feeling that there are quite some users out there who cannot and
> don't want to easily update their compiler.
> So I decided to leave the workaround in the comment to give a hint
> to a quick fix.

ok, so if Debian's built-in cross compilers are indeed that old and we
want to support those (that's ok with me), then let's fix it properly.

> 
> By "making it intelligent" you mean a macro which does some version
> checking and inserts the .byte sequence if needed? Are there any
> archetypes of such code?
> 
Yes, see arch/arm/include/asm/opcodes-*.h

-Christoffer