Hello,
I'm using an LPC1788 with RTX and RL-FlashFS with a EFS configured on a NOR chip.
I have setup a flash device description file to use 4KB sectors instead of 64kB blocks.
Here is a snippet:
#define FLASH_DEVICE \ DFB(0x1000, 0x300000), /* Block Size 4kB */ \ DFB(0x1000, 0x301000), /* Block Size 4kB */ \ DFB(0x1000, 0x302000), /* Block Size 4kB */ \ DFB(0x1000, 0x303000), /* Block Size 4kB */ \ DFB(0x1000, 0x304000), /* Block Size 4kB */ \ .... #define FL_NSECT 256
My issue is that sometimes when I delete a file using fdelete(file) several files are deleted.
(depends what files are on the file system and in what order they were added)
Now I started tracing the NOR function calls and this is what I observed:
fdelete: f:\\bar_button_double.png norflash_program_page: 80300ff8 norflash_program_page: 80300ff0 fdelete: f:\\INDEX.HTM norflash_program_page: 80322ff0 norflash_program_page: 80322fe8 fdelete: f:\\waterdrop.png norflash_program_page: 8031eff8 norflash_program_page: 8031eff0 norflash_erase_sector: 8031e000
The 3rd fdelete (waterdrop.png) actually deleted several other files. The obvious difference is the erase call.
Thanks.
M
The block size for NOR flash can not be smaller than the physical sector size of the device.
The efs.EraseSector() function must be configured to erase the virtual block correctly, if the virtual block spans over several physical sectors on NOR flash.
www.keil.com/.../rlarm_efs_erasesector.htm
To give this a bump up the list, I too would be interested in the response to the second section of Marc's question;
- Are smaller block/sector sizes better or worse for EFS?
In the guidelines for sector layout for EFS ( www.keil.com/.../rlarm_fs_spiflashdev_h.htm ) it notes at the bottom of the page;
It is not optimal to define lots of small sectors (256 bytes or smaller). A more optimal solution for the RL-FlashFS is to join several physical sectors into bigger virtual sectors. In this case, the function EraseSector must be modified to erase a virtual sector, not a single physical sector.
However no further guidance is given. As Marc has asked, are smaller or large block/sector sizes better/worse for EFS? If it depends on the proposed use of the file system then what factors contribute to the decision? 256 byte sectors are bad, but should I be looking at 4kB, 32kB, or 64kB and how do I make the decision?
Thanks,
Phil