Please teach UBI
Hello.
Because I do not usually use English, unknown sentences might be written.
It is a basic question.
UBI is an array of the initial of "Unsorted block images". Please teach the meaning of this "Unsorted block images".
Was there a filesystem of "Sorted block images" in the past? What after the filesystem is different as for not sorting block images? Where of UBI is unsorted block images?
I do not understand. Please tell me.
There are another and a question.
It is defined that CONFIG_MTD_UBI_WL_THRESHOLD is 4096. It is thought this is to mean WL is done as difference between a maximum and a minimum of the value of erace counter of PEBs are always in the range of 4096*2(=8192).
Why is it 8192 ?
In a value that is bigger than 8192, isn't it good? Or, isn't it good in a narrower range?
Isn't there what changed by the character of mtd?
Please teach to me.
My best regards.
Signature · 2 lines
tarosa yamamoto E-Mail: [email protected]
Quoted 7 lines · Tarosa
Hello.
Because I do not usually use English, unknown sentences might be written.
It is a basic question.
UBI is an array of the initial of "Unsorted block images". Please teach the meaning of this "Unsorted block images".
Well, you can consider physical erase blocks to be sorted. Then when you put UBI on top, you have logical eraseblocks (LEBs). Each LEB contains an "image" (data), and it is mapped to a PEB (block), and and UBI makes these images to be unsorted in physical level.
So
1. block = physical eraseblock
2. block image - the contents of a physical eraseblocks.
Without UBI, "block images" are sorted.
With UBI, they become "unsorted", in a sense that UBI adds logical layer with mapping, so on the physical level the "block images" become unsorted.
Hence the name. It also means "where" in Latin. IBM guys invented it, not me, so my understanding can be wrong.
Quoted 1 line
Was there a filesystem of "Sorted block images" in the past?
In physical eraseblocks.
Quoted 1 line
What after the filesystem is different as for not sorting block images?
UBI is not file-system at all. It is a layer between MTD and file-system. UBIFS is a file-system which relies on UBI. It name comes from UBI + FS = UBIFS.
Quoted 7 lines
Where of UBI is unsorted block images?
I do not understand. Please tell me.There are another and a question.
It is defined thatCONFIG_MTD_UBI_WL_THRESHOLDis 4096. It is thought this is to mean WL is done as difference between a maximum and a minimum of the value of erace counter of PEBs are always in the range of 4096*2(=8192).
Not 8192, but 4096.
Quoted 3 lines
Why is it 8192 ?
In a value that is bigger than 8192, isn't it good? Or, isn't it good in a narrower range?
This is just a default. For modern flash you may need lower value, this is configurable.
Signature · 2 lines
Best Regards, Artem Bityutskiy (Артём Битюцкий)