On Mon, Jan 28, 2013 at 12:05:35PM +0530, Mandeep Sandhu wrote:

On Mon, Jan 28, 2013 at 2:07 AM, horseriver <horserivers@gmail.com> wrote:

...

hi:)

Is /boot/initrd.img a root filesystem? what is the filetype of it?

Yes, it's a rootfs with minimal stuff needed for booting a workable system. why does this matter. doing 'file /boot/initrd.img....' on my system shows its a gzip compressed file.

...

Can I put initrd.img in a floppy to boot system ?

I think you can. Provided you have the floppy driver compiled into your kernel.

Thanks! Does this /boot/initrd.img file come out when building kernel ? how to build it?

CMIIW.

-mandeep

...

thanks!

_______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

_______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

On Mon, Jan 28, 2013 at 03:07:13PM +0700, Mulyadi Santosa wrote:

On Mon, Jan 28, 2013 at 5:10 AM, horseriver <horserivers@gmail.com> wrote:

...

Does this /boot/initrd.img file come out when building kernel ? how to build it?

you use your distro supplied /sbin/mkinitrd or /sbin/mkinitramfs

Thanks! I mean its content is from where ? After /sbin/mkinitrd , what stuff is needed to fill it ?

-- regards,

Mulyadi Santosa Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com

_______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

On Mon, 28 Jan 2013 06:10:36 +0800, horseriver said:

On Mon, Jan 28, 2013 at 12:05:35PM +0530, Mandeep Sandhu wrote:

...

On Mon, Jan 28, 2013 at 2:07 AM, horseriver <horserivers@gmail.com> wrote:

...

hi:)

Is /boot/initrd.img a root filesystem? what is the filetype of it?

Yes, it's a rootfs with minimal stuff needed for booting a workable system. why does this matter. doing 'file /boot/initrd.img....' on my system shows its a gzip compressed file.

...

Can I put initrd.img in a floppy to boot system ?

I think you can. Provided you have the floppy driver compiled into your kernel.

And assuming the initrd fits on a floppy (which is actually unlikely - even without any kernel modules on it, the initrd to get LVM launched comes in at around 8M. A default Fedora initramfs is closer to 20M. Good luck fitting that on a floppy :) Of course, an initrd on floppy is kind of silly, because you still need to find someplace else to fit the actual kernel - which hasn't fit on a floppy for quite some time.

Thanks!

Does this /boot/initrd.img file come out when building kernel ? how to build it?

Your system should have either 'mkinitrd' or 'dracut' to build the initrd image. Some older systems will have 'mkinitramfs'.

On Tue, 29 Jan 2013 04:06:39 +0800, horseriver said:

...

Of course, an initrd on floppy is kind of silly, because you still need to find someplace else to fit the actual kernel - which hasn't fit on a floppy for quite some time.

Do we must need initrd.img to boot system ?

If your kernel is able to find the root filesystem without any assistance, based on just the built-in drivers and the root= kernel commandline value, you don't need an initrd. However, most distros build basically an 'allmodconfig', which means the required drivers for devices and filesystems are modules and need to be loaded before the root filesystem can be mounted. Also, if you use root-on-LVM or similar, you will need an initrd to issue the LVM command to start up the disks.

...

Your system should have either 'mkinitrd' or 'dracut' to build the initrd image. Some older systems will have 'mkinitramfs'.

I know how to make a initrd image file , but put what data into it?

You put in what's needed to get your root filesystem mounted and get /sbin/init or whatever started. This will, of course, depend on your exact hardware, disk, and kernel configuration (my system only needs to do the LVM thing, as all drivers are built-in. Your system will probably differ).