From mboxrd@z Thu Jan  1 00:00:00 1970
From: Hans de Goede <j.w.r.degoede@hhs.nl>
Date: Wed, 31 Oct 2007 20:38:45 +0000
Subject: Re: [lm-sensors] Utility for creating computate sensors.conf lines
Message-Id: <4728E7D5.1000205@hhs.nl>
List-Id: <lm-sensors.vger.kernel.org>
References: <472841C2.5060701@hhs.nl>
In-Reply-To: <472841C2.5060701@hhs.nl>
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To: lm-sensors@vger.kernel.org

Jean Delvare wrote:
> Hi Hans,
> 
> On Wed, 31 Oct 2007 09:50:10 +0100, Hans de Goede wrote:
>> Hi all,
>>
>> As discussed here is an utility for creating computate sensors.conf lines for 
>> fscher and newer from DMI tables.
>>
>> I wrote it in C as I'm most fluent in that language. I've it attached, shall I 
>> import it somewhere under progs?
> 
> C is definitely not the language I would have chosen for the job, but
> that's your tool so it's really up to you ;)
> 
> Yes, you should add this to the lm-sensors repository, either under etc
> or create for example prog/config and put it there (in which case we
> would move sensors-conf-convert there too.)
> 
> Please first convert the code to stick to the usual coding style, in
> particular indent with tabs and opening curly braces go at the end of
> the line.
> 
> You'll have to add a license statement and copyright at the top of the
> file.
> 

Will do.

>> #include <stdio.h>
>> #include <unistd.h>
>> #include <sys/types.h>
>>
>> int main(void)
>> {
>>    char buf[512];
>>    unsigned int x;
>>    FILE *f;
>>    int i, count, entities_found;;
>>    int in0_mult, in1_mult, in2_mult, in0_offset, in1_offset, in2_offset, vref;
>>    
>>    if (getuid())
>>    {
>>       fprintf(stderr, "Error this program must be run as root because it "
>>                       "invokes / uses dmidecode which requires root rights\n");
>>       return 1;
>>    }
>>    
>>    f = popen("/usr/sbin/dmidecode", "r");
> 
> You could use dmidecode's command line parameters to ease your parsing
> work or at least speed it up. In particular, option -t, and maybe -u.
> 

I tried using -t, but although it works for types that dmidecode knows about 
like 20, it does not work for type 185, when I specify -t 185 I get no output.

>>    
>>    if (!f)
>>    {
>>       perror("Error invoking dmidecode failed");
>>       return 1;
>>    }
>>    
>>    while (fgets(buf, sizeof(buf), f))
>>    {
>>       if (strcmp(buf, "OEM-specific Type\n"))
>>          continue;
>>
>>       if (!fgets(buf, sizeof(buf), f))
>>          break;
>>
>>       if (strcmp(buf, "\tHeader and Data:\n"))
>>          continue;
>>
>>       count = 0;
>>       entities_found = 0;
>>       
>>       while (fscanf(f, "%x", &x) = 1)
>>       {
>>          buf[count] = x;
>>          count++;
>>       }
>>
>>       /* we are looking for what Siemens calls "subtype" 19, the subtype
>>          is stored in byte 5 of the dmi block */
>>       if (buf[4] != 19)
>>          continue;
>>          
>>       /* After the subtype comes 1 unknown byte and then blocks of 5 bytes,
>>          consisting of what Siemens calls an "Entity" number, followed by
>>          2 16 bit words in LSB first order */
>>       for (i = 6; (i + 4) < count; i += 5)
>>       {
>>          if (buf[i] = 1) /* entity 1 5 volt / in1 multiplier and offset */
>>          {
>>             in1_mult   = buf[i + 1] | (buf[i + 2] << 8);
>>             in1_offset = buf[i + 3] | (buf[i + 4] << 8);
>>             entities_found += 0x0001;
>>          }
>>          if (buf[i] = 2) /* entity 2 12 volt / in0 multiplier and offset */
>>          {
>>             in0_mult   = buf[i + 1] | (buf[i + 2] << 8);
>>             in0_offset = buf[i + 3] | (buf[i + 4] << 8);
>>             entities_found += 0x0010;
>>          }
>>          if (buf[i] = 3) /* entity 3 vbat / in2 multiplier and offset */
>>          {
>>             in2_mult   = buf[i + 1] | (buf[i + 2] << 8);
>>             in2_offset = buf[i + 3] | (buf[i + 4] << 8);
>>             entities_found += 0x0100;
>>          }
> 
> Looks to me like these 3 first cases could be refactored easily if you
> had arrays instead of separate variables for in*_mult and in*_offset.
> 
>>          if (buf[i] = 7) /* entity 7 reference voltage */
>>          {
>>             vref = buf[i + 1] | (buf[i + 2] << 8);
>>             entities_found += 0x1000;
>>          }
> 
> The "+="s above should IMHO be "|="s. Granted, it only makes a
> difference if the same entity is described twice, which shouldn't
> happen, but I still think it's cleaner that way.
> 

Actually they are += deliberately, and the bits used are sparse deliberately, 
so that if there is more then one occurrence of an entity entities_found won't 
match, as I don't think thats supposed to happen (most of this is reverse 
engineered, all I have is the fscher "datasheet" which doesn't give much 
details about the layout of the dmi data).

Regards,

Hans

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