Am 01.11.2013 20:22, schrieb Seiji Aguchi:
>>>> +{
>>>> + char id_str[64];
>>>> + u64 id = 0;
>>>> +
>>>> + sprintf(id_str, "%lu%u%d", timestamp, part, count);
>>>> + if (kstrtoull(id_str, 10, &id))
>>>> + pr_warn("efi-pstore: failed to generate id\n");
>>>> + return id;
>>>> +}
>>>
>>> This is just odd. You make a string from three ints and then a parse
>>> it to a int again.
>>
>> Agreed. I liked your ((timestamp * 100 + part) * 100 + count function much
>> more than this.
>
> I was worried that the part and count could be more than 100.
> If it happens, the id may not be unique...
>
> But, currently, size of nvram storage is limited, so it is a corner case.
> I respect your opinion.
What about feeding the bytes of all three integers into a non-cryptographic hash function?
Using this way you get a cheap unique id.
Thanks,
//richard
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