Hi Dmitry,
Can you be more specific about which arago kernel you're using?
Project sources can be found at
http://arago-project.org/git/projects/
In general, the Linux Kernel has a "Documentation" folder at the root of the source which can be perused for options. Additionally, one can grep for specific options of interest. e.g.
Code:
grep -irl ramdisk_size Documentation
The Kernel documentation is also fairly logical. e.g. to learn anout memory
look at memory.txt. To learn about ramfs one can
look in the filesystems folder.
For things you're not sure about the location you can clone the source and use grep to find it.
Edit:
found ramdisk_size in the kernel docs by web searching "kernel.org ramdisk_size". It seems the option is in KB so 49152 is 48MB.