Re: APs from the Kernel Summit run Linux

Kyle Moffett
2005-09-01T03:29:51Z

On Aug 31, 2005, at 16:32:11, Vojtech Pavlik wrote:
> On Wed, Aug 31, 2005 at 08:53:19PM +0100, Russell King wrote:
>
>> On Wed, Aug 31, 2005 at 12:55:12PM -0400, Mark Lord wrote:
>>
>>> I'll try loading the works into another ARM
>>> system I have here, and see (1) if it runs as-is,
>>> and (2) what the disassembly shows.
>>>
>>
>> You can identify ARM code quite readily - look for a large number of
>> 32-bit words naturally aligned and grouped together whose top nibble
>> is 14 - ie 0xE.......
>>
>> The top nibble is the conditional execution field, and 14 is
>> "always".
>
> Didn't find that. Anyway:
>
> The first and third parts contain a repeating 7-byte sequence
>
> 81 40 20 10 08 04 02
>
> near the beginning, while part 2 is padded with zeroes in the same
> place.

That sequence is altered in the first and last repetitions, like this:

88 4020 1008 0402
81 4020 1008 0402
[...]
81 4020 1008 0402
81 4020 1008 04c2

The 4020 and 0402 look oddly symmetrical to me, but that could just
be my imagination.

I wrote a quick perl script to find the number of occurrences of 8-bit
aligned sequences of 16-bits, for all 16-bit values. It has some
interesting (and potentially useful) results.

The script:
http://zeus.moffetthome.net/~kyle/hexfreq

The output:
http://zeus.moffetthome.net/~kyle/dwl.hexmult

Reprocessed output by frequency:
http://zeus.moffetthome.net/~kyle/dwl.hexfreq

Reprocessing command:
<dwl.hexmult sed -re 's/^(.*): (.*)$/\2: \1/g' | sort -gr >dwl.hexfreq

Cheers,
Kyle Moffett

--
Somone asked me why I work on this free (http://www.fsf.org/philosophy/)
software stuff and not get a real job. Charles Shultz had the best
answer:

"Why do musicians compose symphonies and poets write poems? They do
it because
life wouldn't have any meaning for them if they didn't. That's why I
draw
cartoons. It's my life."
-- Charles Shultz