Hi all,
Excuse me.
》However, calculations limit any one partition to *2^31* chunks in total. ie
a
》total partition of *2^41*.
Chunk ID is 32 bit long. That should be 2^32 in paper. But I don't know
why Charles means 2^31 here. Are there 2 id can't be used in defalut or Is
it his carelessness?
So that should be 2^32 ^ 2^11= 2^43B, when Chunk size is 2kb.
Thanks!
>
>
> 2008/10/21 Charles Manning <manningc2@actrix.gen.nz>
>
>
>> > Hi
>> > I want to know clearly the maximam file system size for YAFFS2 can
>> > handle.
>> > In file ysffs_guts.h, there're ysffs_Tags structure:
>> > typedef struct {
>> > unsigned chunkId:20;
>> > unsigned serialNumber:2;
>> > unsigned byteCount:10;
>> > unsigned objectId:18;
>> > unsigned ecc:12;
>> > unsigned unusedStuff:2;
>> >
>> > } yaffs_Tags;
>> > I can calculate the maximum file system size YAFFS2 can handle by
>> > following algorithm:
>> > (2^20)*(2^18)*(2kb)= 2^49B //Chunk size is 2kb
>> > Am I right?
>> > Appreciate for your reply! Thanks.
>>
>> While you have chosen the wrong structure here (yaffs_Tags is only
>> relevent to
>> the yaffs1 mode of operation), the basic idea is almost correct.
>>
>> yaffs2 uses the yaffs_PackedTags2 structure. This allows up to 32 bits for
>> the
>> chunk Id. That limits any particular file to 2^42 (assuming 2048-byte
>> chunks).
>>
>> However, calculations limit any one partition to 2^31 chunks in total. ie
>> a
>> total partition of 2^41.
>>
>> However, all the structures use RAM and thus real-world RAM limitations
>> are
>> more likely to cause problems first.
>>
>> -- Charles
>>
>>
>>
>>
>>
>
>
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