just trying to clarify some issues for a little HOWTO i'm writing,
so i'll start with some really fundamental questions:
* as i read it, the Kconfig variable CONFIG_BLK_DEV_INITRD entirely
dictates whether you have any sort of initrd support whatsoever --
that includes in-kernel cpio image, or any external initial ramdisk,
right? it seems pretty clear, but i just wanted to make sure i
wasn't missing something subtle.
* in arch/x86/kernel/setup_32.c, you can see how, based on that
Kconfig variable, the setup routine will access an external
initrd image that was handed in by the boot loader:
#ifdef CONFIG_BLK_DEV_INITRD
if (boot_params.hdr.type_of_loader && boot_params.hdr.ramdisk_image) {
unsigned long ramdisk_image = boot_params.hdr.ramdisk_image;
unsigned long ramdisk_size = boot_params.hdr.ramdisk_size;
unsigned long ramdisk_end = ramdisk_image + ramdisk_size;
...
and will set initrd_start and initrd_end accordingly. i'm guessing
that, even if you don't select initrd support, the boot loader will
still have loaded that information at those locations -- you just
won't bother accessing it, is that correct?
* while CONFIG_BLK_DEV_INITRD identifies general initrd support, you
still need to additionally select CONFIG_BLK_DEV_RAM if you want
external initrd support that isn't just a compressed cpio image, but
is instead a filesystem image (perhaps ext2). right?
that should do for now.
rday
========================================================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA
http://crashcourse.ca
========================================================================
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