On Sunday, March 13, 2016, Greg KH <greg@kroah.com> wrote:
On Sat, Mar 12, 2016 at 04:29:08PM +0800, Woody Wu wrote:
> My question is, is there such a kernel parameter to do the job? Probably there
> is a non-parameter solution like passing the initramfs address in a register
> when a boot loader transfer control to the kernel, but this is not an option to
> me since my boot loader (u-boot) does not support doing this. Thanks.
You have the source to your bootloader, I suggest you fix that up to
support this if you want it, not much the kernel can do on it's own
here, sorry.
But the kernel document says,
External initramfs images:
--------------------------
If the kernel has initrd support enabled, an external cpio.gz archive can also
be passed into a 2.6 kernel in place of an initrd. In this case, the kernel
will autodetect the type (initramfs, not initrd) and extract the external cpio
archive into rootfs before trying to run /init.
This has the memory efficiency advantages of initramfs (no ramdisk block
device) but the separate packaging of initrd (which is nice if you have
non-GPL code you'd like to run from initramfs, without conflating it with
the GPL licensed Linux kernel binary).
It can also be used to supplement the kernel's built-in initramfs image. The
files in the external archive will overwrite any conflicting files in
the built-in initramfs archive. Some distributors also prefer to customize
a single kernel image with task-specific initramfs images, without recompiling.
So I am thinking, can I from my bootloader load a cpio.gz into ram and start kernel with a command line "initrd=0x30000000"? Wii this work? And, in this case should I also pass kernel with someilike "roo=/dev/ram"? Thanks.
-woody
I found the initrd=address works! No root= need to be passed. Only let u-boot load a cpio.uboot image into physical memory and set the correct kernel command line, my problem solved. :-)