The boot loader puts the initial ramdisk somewhere, and tells the kernel where that is when it hands control over to the kernel. Once the kernel starts running, the ramdisk can increase in size by marking parts of the buffer cache as dirty. If you add lots of data to a ramdisk, it will end up being stored all over the place.
you can use mtd to create a ramdisk at a fixed physical address, look at modules slram and phram. you can use mkfs to put a (temporary) filesystem onto the resulting /dev/mtd# devices and mount it as usual.
Try reading the kernel documentation...
Take a look at:
linux-2.6.*/Documentation/ramdisk.txt
The boot loader puts the initial ramdisk somewhere, and tells the kernel where that is when it hands control over to the kernel. Once the kernel starts running, the ramdisk can increase in size by marking parts of the buffer cache as dirty. If you add lots of data to a ramdisk, it will end up being stored all over the place.
mtd
you can use mtd to create a ramdisk at a fixed physical address, look at modules slram and phram. you can use mkfs to put a (temporary) filesystem onto the resulting /dev/mtd# devices and mount it as usual.