How to use NAND Flash device simulator

[laoniaokkk]

I add NAND simulation under sim/nsh configuration, when 'nand' is executed, the ‘/dev/nand‘ device will be generated, but when using "mkfatfs /dev/nand" or "echo hello > /dev/nand", some errors will be generated and the program will be killed. I don't know how to use this device, actually I want to try to port the YAFFS2 filesystem based on this emulated NAND, and it has been successfully ported in bare metal, I need some help. In addition, there are some problems with this NAND driver:

1. Some debugging and logging must be enabled；
2. Compilation error under HOST_ARM64;
3. SPI NAND cannot be supported

And this is my .config config.txt

Error logs: NuttShell (NSH) NuttX-12.5.1-RC0 MOTD: username=admin password=Administrator nsh> nand nand_ram: [LOWER | initialize] Driver running! nand_wrapper: [UPPER 1 | ioctl] Command: 1537, Arg : 139985771286160 nand_wrapper: [UPPER 1 | ioctl] Done Page size: 512 nsh> echo hello > /dev/nand nand_wrapper: [UPPER 2 | ioctl] Command: 1537, Arg : 139985771083416 nand_wrapper: [UPPER 2 | ioctl] Done nand_wrapper: [UPPER 3 | isbad] Blocks: 0 nand_ram: [LOWER 1 | rawread] Page 0 nand_ram: [LOWER 1 | rawread] Done nand_ram: [LOWER 2 | rawread] Page 1 nand_ram: [LOWER 2 | rawread] Done stack smashing detected : terminated 已放弃 (核心已转储)

[acassis]

Hi @laoniaokkk did you look at https://nuttx.apache.org/docs/latest/applications/testing/nand_sim/index.html ?

The "stack smashing detected" means you are passing some memory limit.

Maybe @resyfer could give you more details. Sarav, could you please take a look?

[resyfer]

Hi @acassis, the execution weirdly stops in-between execution it seems. I am not too knowledgeable about the memory limits in the simulator.

For me the stack trace for mkfatfs on /dev/nand sort of went like this: mkfatfs.c:mkfatfs():L326 fs_open.c:open():L453 fs_open.c:nx_vopen():L300 fs_open.c:file_vopen():L199 fs_blockproxy.c:block_proxy():L167 bchdev_register.c:bchdev_register():L61 bchlib_setup.c:bchlib_setup():L75 fs_openblockdriver.c:open_blockdriver():L86 fs_mtdproxy.c:mtd_proxy():L164

And in ftl.c, it crashes in between this area. My config:

• Disabled:
  • CONFIG_FTL_READAHEAD
  • CONFIG_FTL_WRITEBUFFER

Thus FTL_HAVE_RWBUFFER is also disabled. So the entire area has nothing to crash on, and I think, like @acassis said, it might be due to a memory limit. I am not sure what can prevent this, and I need help on this.

Both mkfatfs and echo commands provided by @laoniaokkk stop at this point.

nand (the device simulator) relies heavily on memory. Currently, the entire memory is allocated in an entire contiguous chunk, which might be a cause. Of course this can be changed to be more lazy in nature.

The sim device is still experimental so a lot of features are missing or might not work in certain circumstances. It has been tested mostly by using littlefs. Thank you for pointing this out!