[Peter Oh <p...@innopath.com>] > > Thank you a lot for your reply. > > Now I'm almost clear except this one. > If I assume that I have initramfs file as the name of 'ramdisk.img'
Yup. ramdisk.img is a gzip'd cpio image. > How can android kernel find the location of 'ramdisk.img' exists? > If there is 'root=' option, kernel can try to find the location of > 'ramdisk.img' from the location of 'root='. > But if kernel option does not have 'root=' option, > How kernel knows the location of ramdisk.img? The bootloader passes the ramdisk size and location via ATAGs. See Documentation/arm/Booting in the linux kernel sources. > Does android kernel also usr 'root=' option to find out the location of > 'ramdisk.img'? > Can I see what the typical 'Kernel command line' option for android is? Nothing special really. I used "mem=101M console=ttyMSM2" on 7201A SURF, for example. > Really my best regards. > Peter Oh > > -----Original Message----- > From: android-porting@googlegroups.com > [mailto:android-port...@googlegroups.com] On Behalf Of Brian Swetland > Sent: Wednesday, February 11, 2009 12:28 AM > To: android-porting@googlegroups.com > Subject: [android-porting] Re: How to use initramfs for root filesystem? > > > > When booting with initramfs, the kernel creates a tmpfs at /, unpacking > the initramfs (typically a gzip'd cpio archive) into it. Then it runs > /init (I believe there is actually a short list of programs it tries to > run on / in a specific order, but I'd have to look at the kernel sources > to verify this). > > It's expected that the init process started from initramfs will know how > to get everything else going. In the android world, this involves > /init.rc scripting what to mount where, etc. > > Brian > > [ebmajor <p...@innopath.com>] > > > > Dear all, > > > > I'm trying to understand how initramfs, especially 'init' program is > > used as a root filesystem. > > Usually I've used 'root=/dev/mtdblock0 rootfstype=jffs2' in kernel > > command line for root filesystem and my 'init' program > > is laid in mtdblock0 so kernel can find where the 'init' program > > exists. > > > > But I read initramfs does not required 'root=' command line. > > So, if I don't type 'root=' in kernel command line, how the kernel > > finds out where the 'init' program exists? > > and what kind of filesystem is using for the block that 'init' program > > exists? > > > > Simply asking, > > Can I use kernel command line without 'root=' option? If I can, how > > can I use? > > > > Sincerely. > > > > > > > > > > > > --~--~---------~--~----~------------~-------~--~----~ unsubscribe: android-porting+unsubscr...@googlegroups.com website: http://groups.google.com/group/android-porting -~----------~----~----~----~------~----~------~--~---
