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Valued Contributor III

Write filesystem on flash



I'm working with nios2 nommu and I have a 8 MB SDRAM and 8 MB CFI FLASH. 


For create a filesystem in a flash I create a kernel with a miminal service (without network and webserver) to start and copy all the files in ram to flash, in my rc the configuration is 


hostname uClinux mount -t proc proc /proc -o noexec,nosuid,nodev mount -t sysfs sysfs /sys -o noexec,nosuid,nodev mount -t devpts devpts /dev/pts -o noexec,nosuid mount -t jffs2 /dev/mtdblock0 /mnt mkdir /mnt/mnt mkdir /mnt/proc mkdir /mnt/sys mkdir /mnt/tmp mkdir /mnt/var/ mkdir /mnt/var/tmp mkdir /mnt/var/log mkdir /mnt/var/run mkdir /mnt/var/lock mkdir /mnt/var/empty cp -a /bin /mnt cp -a /dev /mnt cp -a /etc /mnt cp -a /home /mnt cp -a /init /mnt cp -a /lib /mnt cp -a /sbin /mnt cp -a /usr /mnt cp /home/rc /mnt/etc 



But when my image is larger then 2 MB (when my romfs is a little bigger) I have problem to write on flash memory, when the kernel try copy the /home to /mnt the RAM "crash" I have a message with stack trace call. 



Somebody knows a best pratice to write the files system on flash (for production)? 

There's a way to create a .FLASH or .BIN of a initramfs_data.cpio.gz to write on flash directly by jtag or u-boot? 



Thank you very much. 



Caio Pereira 



Caio Pereira 

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Valued Contributor III

Re: Write filesystem on flash

I got write the filesystem in my flash , but this method has some problems yet. 



1) Download the mtd-utils (for mkfs.jffs2) 

In my case (Ubuntu) 

sudo apt-get install mtd-utils 


2) Generate a romfs in a uClinux-dist 

make romfs 


3)Generate a device_table (like a romfs_list file in /vendor/Altera/nios) 


In the romfs_list we have something like this# Device Name mode uid gid type major minor 

/dev/tty 666 0 0 c 5 0 

/dev/kmem 640 0 0 c 1 2 

/dev/mtd0 640 0 0 c 90 0 

/dev/mtd1 640 0 0 c 90 2 

/dev/mtd2 640 0 0 c 90 4 



In the device_table we need write in another mode like# <name> <type> <mode> <uid> <gid> <major> <minor> <start> <inc> <count># where name is the file name, type can be one of: # f A regular file# d Directory# c Character special device file# b Block special device file# p Fifo (named pipe) 

/dev/mem c 640 0 0 1 1 0 0 - 

/dev/kmem c 640 0 0 1 2 0 0 - 

/dev/null c 640 0 0 1 3 0 0 - 

/dev/zero c 640 0 0 1 5 0 0 - 

/dev/random c 640 0 0 1 8 0 0 - 

/dev/urandom c 640 0 0 1 9 0 0 - 

/dev/tty c 666 0 0 5 0 0 0 - 


You need change this file for your system and save with device_table.txt (this is normal for nios linux with mmu) 



4) Creating a file system 


We would create this file in nios2-linux/uClinux-dist/image 


mkfs.jffs2 -l -e128KiB -p -d ../romfs -D device_table.txt -o rootfs.jffs2 

This file is ready to write by bootloader 


After this we have a rootfs.jffs2 file , but this process ins't ok, I having problem with erase_block size 


Node at 0x0020ff20 with length 0x000008b1 would run over the end of the erase bk 

Perhaps the file system was created with the wrong erase size?  

jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0020ff24: 0x08b1 id 

jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0020ff28: 0x4c30 id 




5) Burning flash 

In my case I'm using jtag  

My CFI flash is partitioned: 


Creating 2 MTD partitions on "physmap-flash.0":  

0x000000200000-0x000000800000 : "romfs/jffs2"  

0x000000000000-0x000000200000 : "loader/kernel"  


For convert binary file to .srec file we need use a bin2flash tool: 


bin2flash --input=rootfs.jffs2 --location=0x200000 --output=rootfs.flash 


Now we need write the rootfs.flash in CFI flash using nios2-flash-programmer tool 

nios2-flash-programmer --base=0x2000000 rootfs.flash 


After this we boot with a kernel image monting a jffs2  



When I get fix my problem with erase_block I return with another reply with the fix 



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