John Rigg <dev1@???> writes:
> On Fri, Jan 01, 2016 at 12:26:41PM -0500, Steve Litt wrote:
>> If / is formatted ext4, it can be mounted directly by a kernel with ext4
>> drivers, no initramfs needed.
>
> Wasn't the original reason for having an initrd that the boot loader,
> probably LILO at the time, couldn't handle a kernel image above a
> certain size? (My recollection could be faulty here, so corrections
> welcome).

Oh wow. That got twisted :-). LILO loads a kernel image via BIOS calls
and "10,000 years ago" (ie, I've encountered this problem once, on my
very first Linux install, RH3.0.3, and then "nevermore" despite I've
been using LILO all the time), the BIOS couldn't load anything beyond
"the 1024 cylinder boundary" (504M). Hence, a kernel supposed to be
loaded by LILO had to be located in the first 504M of a disk. This
becomes a problem when dual-booting similarly ancient "other PC OSes"
(in my case, OS/2 Warp 4) which insist on residing on the first primary
partition.

But there's no reason why the first entry of the MBR partition table
must point to the beginning of the disk. Hence, one can create a primary
partition #2 at the beginning of the disk which is large enough to hold
a Linux /-filesystem, followed by a primary paritition #1 behind it
holding "the legacy OS", followed by whatever other partition the
Linux-system need and then happy dual-boot away.