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Re: Debian-installer use of initrd (was Re: CONFIG_BLK_DEV_RAM=y)

On Wed, Sep 16, 2009 at 1:02 PM, Ben Hutchings <ben@decadent.org.uk> wrote:
> On Wed, Sep 16, 2009 at 12:24:00PM -0400, Lee Winter wrote:
>> On Wed, Sep 16, 2009 at 12:07 PM, Frans Pop <elendil@planet.nl> wrote:
>> > On Wednesday 16 September 2009, Ben Hutchings wrote:
>> >> > Is installation from floppies still supported?  If so, can they be
>> >> > converted to using initramfs?
>> >>
>> >> Actually, I don't see how this can work today since ext2 is a module...
>> >> Has anyone tested that these work in lenny?
>> >
>> > There are no floppy images in Lenny. We stopped building them because the
>> > kernel would no longer fit on the boot floppy. There was some discussion
>> > on having a separate kernel for D-I floppy installs (it would still fit
>> > with a number of unneeded optionsdisabled), but that was blocked by the
>> > kernel team as they did not want to build a separate flavor for that
>> > purpose.
>> But the installer does not need a separate kernel.  It just needs a
>> smaller one. And the kernel team are already supporting several
>> smaller (older) kernels.
> We (primarily Dann Frazier) provide security support for oldstable and
> stable, and we apply selected bug fixes and hardware support improvements
> to stable.

OK, so those are all reasonable candidates for use in booting the installer.

>> So why can't all of the the lenny/squeeze installations be done with
>> the kernel from etch or even sarge?  This would seem to be completely
>> within the jurisdiction of the installer team.  Am I missing
>> something?
> The fact that those kernels lack support for many devices that are common
> in currently shipping hardware, and for the filesystems that users may
> wish to create at installation time.

OK, the smaller kernels do not have the feature set necessary to
operate the installer.  But they probably have the feature set
necessary to boot the installer.  The boot kernel does not need to
support all of the installer features.  The boot kernel only needs to
acquire the current kernel and associated initrd.

Now a machine for which floppies are the best install medium is hardly
going to have the latest and greatest hardware, so the presence of
that hardware is an implicit violation of the premise that floppies
are the user's best option for getting Debian going.  So the smaller
kernel probably does support the network hardware on the kind of
machines floppies are /g/o/o/d/ adequate for.

It appears to me that the floopy boot software only needs to do three things.
   -- load from a cold-boot floppy
   -- (down)load the kernel and associated initrd [1]
   -- run grub aimed at the downloaded images

[1] If the network hardware is truly arcane the files could be loaded
from successor floppies.  Or from any other medium that happens not to
be bootable such as an LS-120, USB drive, CD drive (worst case might
be a Bantam Backpack over a parallel port), or network card.

How would the presence of the latest and greatest hardware interfere
with that sequence?  I suspect that it would not.  The issue would be
the lack of hardware contemporary to the smaller kernel.  But that
issue is a non-problem for the target machine population.

-- Lee

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