Hi Stefano, Yes, board flash is NOR-type. I will try to check the flash operation scheme and also the use of the MTD partitions.
Regards, Alberto 2010/11/26 Stefano Babic <[email protected]> > On 11/26/2010 08:28 AM, Alberto Caballero wrote: > > Hi, > > Hi, > > > > > At my project, I will have a data configuration file stored in the board > > Flash memory using an U-Boot filesystem image. At the initialization > stage, > > I read the image from the Flash and store it in the Linux filesystem. > > > > Of course at the U-Boot prompt I am able to check that image header at > Flash > > is correctly stored and all the bytes has the right values. I was > wondering > > if this has something to do with first access to mapped memory. > > You can try to read the flash at the required address twice and check if > the first byte is always wrong. However, with mmap() you are bypassing > the whole linux flash driver that it is responsible to provide the same > interface independently from the underlying hardware. > > And again, I suppose you have NOR flash on board, because reading NAND > flash with mmap simply does not work... > > > > > When Linux initializes it creates a series of MTD partitions by its own. > > I do not think so. Linux creates partitions as you asked to do. Check > your DTS file (I assume you are using a recent kernel) and modify the > partition's size according to your requirement. > > > Now > > the data in the Flash will be overlapped in two partitions so I will try > to > > use just one of them. > > Then it seems you have to adapt the configuration of the partitions. > > > > > Regarding the mmap usage, I was able to check with another board with > > another PowerPC processor using ELDK also, and in this case there is no > > issue with Flash access. > > This does not depend on ELDK. Reading directly the flash chip can work > on some hardware, but it could be unreliable with some other chips. For > example, you do not know which was the last operation issued on the > chip. If the flash driver has sent a CFI-Query, what you read is the > internal mapping of the chip. Using the MTD subsystem you are sure that > the flash driver will take care of all internal details. > > Best regards, > Stefano Babic > > -- > ===================================================================== > DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany > Phone: +49-8142-66989-0 Fax: +49-8142-66989-80 Email: [email protected] > ===================================================================== >
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