Subject: Re: a question about arm-gcc
To: Danny Lau <liudengcs@gmail.com>
From: Danny Lau <liudengcs@gmail.com>
List: port-arm
Date: 06/09/2006 14:28:09
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On 6/9/06, David Laight <david@l8s.co.uk> wrote:
>
> On Tue, Jun 06, 2006 at 06:13:06PM +0800, Danny Lau wrote:
> > Hi, all
> >
> > I am rewiting gzboot to let messages be dumped to the LCD panel rather
> > than the COM port,and the arm--netbsdelf-gcc is generated by command "
> > build.sh -m evbarm tools". For some reasons, I feel that the compiler
> cann't
> > output correct binary code.
>
> One this to look at is whether you have the 'misaligned access' trap
> enabled.  At least some versions of gcc for arm will do 32bit reads
> from misaligned addresses [1] in order to read 16bit quantities.
>
>        David
>
> [1] which rotate the word so that the addressed byte ends up in the LSB
> of the registers (if LE).
>
> --
> David Laight: david@l8s.co.uk
>

Thank you. Please tell me how can I enable the 'misaligned access' trap. I
look for the gcc manual and find a -Wpacked option, is this? Or, it is a
hardware option?

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<br><br>
<div><span class="gmail_quote">On 6/9/06, <b class="gmail_sendername">David Laight</b> &lt;<a href="mailto:david@l8s.co.uk">david@l8s.co.uk</a>&gt; wrote:</span> 
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">On Tue, Jun 06, 2006 at 06:13:06PM +0800, Danny Lau wrote:<br>&gt; Hi, all<br>&gt;<br>&gt; I am rewiting gzboot to let messages be dumped to the LCD panel rather
<br>&gt; than the COM port,and the arm--netbsdelf-gcc is generated by command &quot;<br>&gt; build.sh -m evbarm tools&quot;. For some reasons, I feel that the compiler cann't<br>&gt; output correct binary code.<br><br>One this to look at is whether you have the 'misaligned access' trap
<br>enabled.&nbsp;&nbsp;At least some versions of gcc for arm will do 32bit reads<br>from misaligned addresses [1] in order to read 16bit quantities.<br><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; David<br><br>[1] which rotate the word so that the addressed byte ends up in the LSB
<br>of the registers (if LE).<br><br>--<br>David Laight: <a href="mailto:david@l8s.co.uk">david@l8s.co.uk</a><br></blockquote></div><br>Thank you. Please tell me how can I enable the 'misaligned access' trap. I look for the gcc manual and find a -Wpacked option, is this? Or, it is a hardware option?

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