[Click] AlignmentInfo Question

[Eddie Kohler]

Huh.  Is "int" 64 bits wide on AMD64?  I'd appreciate it if you sent me 
your "config.log" file (don't cc the list, those files are large) so I 
can take a look.

Eddie


Fischofer William-B09792 wrote:
> Actually, this is running on Linux on an AMD64 box.  I'll be moving this
> to a PPC-based platform later but I wanted to get things running on an
> x86-compatible box first.  I did look up click-align and will use that
> if it seems advisable but I was just surprised to get that error message
> (even moreso now that you say I shouldn't have gotten it in the first
> place).
> 
> Bill
> 
> -----Original Message-----
> From: Eddie Kohler [mailto:kohler at cs.ucla.edu] 
> Sent: Monday, March 26, 2007 1:05 PM
> To: Fischofer William-B09792
> Cc: click at amsterdam.lcs.mit.edu
> Subject: Re: [Click] AlignmentInfo Question
> 
> Hi Bill,
> 
> I guess you are not running on an x86-compatible machine?  On x86, there
> is no penalty to accessing a word that isn't aligned; on non-x86 it can
> cause a crash.  The "click-align" tool is made to introduce
> AlignmentInfo elements that inform elements of what alignment they
> should expect.  Rather than "click FILE.click", try "click-align
> FILE.click | click".
> 
> Eddie
> 
> 
> Fischofer William-B09792 wrote:
>> I have the following elementclass:
>>  
>> elementclass TrafficClassifier {
>>    $interface |
>>    input ->
>>    c0 :: Classifier (12/0806 20/0001,            // ARP Requests
>>                           12/0806 20/0002,            // ARP Replies
>>                           12/0800,                        // IPv4
>> Packets
>>                            -);                                 //
>> Everything else
>>    c0[0] -> [0]output;
>>    c0[1] -> [1]output;
>>    c0[2] -> [2]output;
>>    c0[3] -> ToHost($interface);                    // Send all
>> "uninteresting" traffic to host
>> }
>>  
>> Which is then used as follows:
>>  
>> FromDevice(eth0) -> tc0::TrafficClassifier(eth0);
>> FromDevice(eth1) -> tc1::TrafficClassifier(eth1); ...etc.
>>  
>> However this results in the following error messages from Click:
>>  
>> While configuring 'tc0/c0 :: Classifier':
>>   no AlignmentInfo available: you may experience unaligned accesses
>>  
>> I'm not quite sure what this means or what I should do about it.  I 
>> can make the message go away if I insert the line:
>>  
>> AlignmentInfo(Classifier 4 0);  // Seems to work but is this what I 
>> really need?
>>  
>> Into my TrafficClassifier definition but I'd like to understand what's
> 
>> really going on here.  The online docs are pretty terse in this area.
> 
>> Any reading suggestions for better understanding this stuff?
>>  
>> Thanks much.
>>  
>> Bill Fischofer
>> _______________________________________________
>> click mailing list
>> click at amsterdam.lcs.mit.edu
>> https://amsterdam.lcs.mit.edu/mailman/listinfo/click
> 
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