how to update mounted sd card file directory in Linux ?

exds75 · 08-21-2019, 05:02 AM

Hi Linux,

I am working on zynq AMP project (linux on cpu0 + bare metal app on cpu1).

bare-metal app on cpu1 realizes shell utilities (ls / rm / cat / write file / pwd) for sd card.
Linux on cpu0 can also mount sd card with

# mount /dev/mmcblk0p1 /mnt/
# ls /mnt

However, the new file created by cpu1 does not show in linux on cpu0.

For example, there are 7 files on sd card. After system boot up, cpu1 creates 1 new file (i.e., name aaaa.1234), then "ls" on cpu1 shows total 8 files. Then mount sd card in linux on cpu0, "ls" on cpu0 only shows original 7 files.

Further，I create a new file in linux on cpu0 (i.e., name bbbb.5678, then "ls" on cpu0 shows total 8 files). Then I try "ls" 10 more times on cpu1, which still shows total 8 files, but aaaa.1234 has been replaced by bbbb.5678> In other words, cpu1 has updated file directory and synchronized to cpu0, though aaaa.1234 lost.

My question is how to force linux on cpu0 update file directory and synchronized to cpu1 to show aaaa.1234 created by cpu1.

Please advise, thanks in advance.

Mike

rtmistler · 08-21-2019, 05:22 AM

Quote:

Originally Posted by exds75

# mount /dev/mmcblk0p1 /mnt/
# ls

If you did solely this, you didn't change to /mnt which is the mount point.

syg00 · 08-21-2019, 05:33 AM

Only cluster-aware filesystems can be concurrently updated on disparate systems. You don't say what f/s you are using, but I'd guess it's one of the "standard" linux ones. You cannot do what you did without breaking things - maybe the entire f/s itself.

Without knowing anything, I'd say you need to do register a messaging channel between the 2 environments and use the Linux system to do all file updates. How you then read the updates from the bare-metal side is your concern.

exds75 · 08-21-2019, 05:56 AM

Thanks for quick reply.

Rootfs was generated according to

https://xilinx-wiki.atlassian.net/wi...odify+a+Rootfs

arm_ramdisk.image.gz ==> uramdisk.image.gz

mkimage -A arm -T ramdisk -C gzip -d arm_ramdisk.image.gz uramdisk.image.gz

system boots from qspi memory (BOOT.bin + uImage + devicetree.dtb + uramdisk.image.gz).

Problem is that data was collected by bare-metal app and then stored in files. I expect Linux to take the data file(s) and draw picture/curve ~~

Quote:

Originally Posted by syg00

Only cluster-aware filesystems can be concurrently updated on disparate systems. You don't say what f/s you are using, but I'd guess it's one of the "standard" linux ones. You cannot do what you did without breaking things - maybe the entire f/s itself.

Without knowing anything, I'd say you need to do register a messaging channel between the 2 environments and use the Linux system to do all file updates. How you then read the updates from the bare-metal side is your concern.