Hi Denis,


>> +static void sim_efust_read_cb(int ok, int length, int record,
>> +				const unsigned char *data,
>> +				int record_length, void *userdata)
>> +{
>> +	struct ofono_sim *sim = userdata;
>> +
>> +	if (!ok)
>> +		goto error;
>> +
>>  	if (length < 1) {
>>  		ofono_error("EFust shall contain at least one byte");
>>  		goto out;
>> @@ -1073,6 +1096,12 @@ static void sim_efust_read_cb(int ok, int length, int
>record,
>>
>>  out:
>>  	sim_retrieve_imsi(sim);
>> +	return;
>> +
>> +error:
>> +	ofono_sim_read(sim, SIM_EFSST_FILEID,
>> +			OFONO_SIM_FILE_STRUCTURE_TRANSPARENT,
>> +			sim_efsst_read_cb, sim);
>>  }
>
>That is really not how it works.  If the file ID is the same then you
>need some other information to determine whether this is a phase 3 or a
>phase 2 SIM.  Look at how EFecc reading in voicecall.c is done.  In
>other words, this function needs to make an intelligent decision whether
>this is EFsst or EFust.
>
>In your case the only heuristic we have is EFphase, which is mandatory
>for all Phase 2 SIMs (and absent in all Phase 3 SIMs).

Last time, you mentioned " 3G device + 3G sim -> EFust and EFest, while 2G device + 3G sim -> EFsst". And I think EFphase only means the SIM phase. So just using SIM phase to do the judgement would put us in a risk if we have a phase 3 SIM and 2G device, right? You also mentioned this is the best way we currently have. Do you hint we have no (general) way to get the phase of device?

But I still think there is some problem here: For this case, EFust and EFsst have the same file id and type. So I suppose they can't co-exist in the SIM file system. Otherwise, we couldn't read them by just using the file id and file type. If so, and if I were a SIM manufacturer, how should I decide which one, EFust and EFsst, will be put in? I would have no knowledge what the phase of user's device. So the rule to obey is to have my choice match the EFphase. That is, 3G sim -> EFust and 2G sim ->EFsst.

Another two related questions: 1) Can we have two files with different id but same purpose, one for phase 2 and the other for phase 3, coexist in SIM file system? Thinking about if we change the id of EFsst. This case also hints one of them must be invalid if it's allowed. 2) Can we have two files with same id but different types coexist in SIM file system? According to the assumption of current code with EFecc, I think the answer is no. Just need a confirmation. 

Regards,
-Yang