Re: Areas of Emdebian to integrate into Debian
Brendan:
On Mon, Apr 4, 2011 at 4:18 PM, Brendan Simon <Brendan@brendansimon.com> wrote:
>
> I've seen other distros also use the kernel with uclibc initramfs, then
> switch/mount rootfs using glibc. It obviously works but it makes me feel
> uneasy. I'd feel more comfortable if the same libraries were in initramfs
> and main rootfs. Indeed it may be that the external fs does not even have
> libc and other necessary boot files. They could stay as part of the
> initramfs and the external fs could have everything else. Yes ??
The problem I see with this is that compared with uClibc, glibc is
HUGE. I just can't see using glibc as part of an initramfs. The
risks of using uClibc in one place but glibc in the other are
completely manageable; the initramfs has much more limited
functionality, and doesn't need to chance much, so testing to a high
degree of confidence it before deployment is realistic.
Even on the lowest-end embedded systems, having an initramfs
unexpectedly (to some) makes a lot of sense. It lets me get away with
a brain-dead bootloader, and defer the mkfs.jffs2, ubifs, etc. etc.
etc. to the initramfs. Then I pivot to the final root filesystem.
And if for some reason the root filesystem isn't there, I get the
functionality of the initramfs to help me recover.
In particular, a suitable initramfs lets me wget raw NAND images for
the target platform, and also have a small web server for diagnosing
hardware and other problems. I can't do that with a bootloader unless
the bootloader has TCP/IP. And any bootloader that has TCP/IP is too
sophisticated for me to feel comfortable using it. :)
I'm talking about a target system that has 64MB of NAND, total.
That's all the storage there is. I'll gladly eat 4MB of that for a
kernel and initramfs that gives me in return a nearly un-brickable
system. Any larger than that, however, and I really start to feel the
pinch.
And before you all tell me to just get a larger system, I'll just say
that if you can do real work in 64MB of flash, a whooooooole lot of
interesting possibilities open up--- and I can prove it to you.
Emdebian is making that possible for me. But that's a topic for
another email. :)
b.g.
--
Bill Gatliff
bgat@billgatliff.com
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