GRUB vs LILO

GRUB vs LILO

[Trevor Woolven]

Does anyone know if GRUB has an in-built limit to the size of DOC you
can use it with?

I've got a 4MB DOC2000 and a 24MB DOC2000, both with very similar
filesystems & kernels on. I can boot my system (from hard-disk or DOC)
using LILO (with Dvir Oren's patch applied) with either device installed
but GRUB will only allow me to use the smaller one.

My command line is:
grub> kernel (hd0,0)/mtd/bzImage root=/dev/hda5

and I get:

  [Linux-bzImage, setup=0x800, size=0x88440]

Selected item cannot fit into memory

Any help much appreciated.

Thanks

Trevor.
-- 
Trevor Woolven - Director of Customer Applications Engineering
Zentropix Inc - a Lineo company

Tel: +44 (0)1273 234 647	 Fax: +44 (0)1273 704 482

Visit http://www.zentropix.com/ for Real Time Linux Tools
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Re: GRUB vs LILO

[David Woodhouse]

trevw@zentropix.com said:
> 
>   [Linux-bzImage, setup=0x800, size=0x88440]
> Selected item cannot fit into memory 

This is because the M-Systems firmware takes up a large chunk of your system 
RAM for caching block attributes - this is proportional to the size of the 
DiskOnChip, naturally.

The code I'm currently hacking into Grub will drive the DiskOnChip directly, so
you can remove the M-Systems firmware. My Grub code doesn't do any caching - so
it'll be a tad slower, but it'll work on bigger devices. 



--
dwmw2




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Resume from Flash

[Andreas Kotes]

Hi!

I'd to do resume-from-flash with Linux and DoC 2000, this appears to be
the fastest possibility to get an embedded system up and running ..

Has anyone done this yet? Any suggestions? Any hints/pointers?

I'll start playing around the next few days, and would appreciate any
input you'd like to give. Any results achieved in my/our development will
go back to the community und either GPL or BSD-style license.

Kind regards

   Count

-- 
  -= Andreas Kotes - mailto:count@flatline.de - Questions? Just ask =-
 -= Are you doing what you are able to do to support peace on earth? =-
-= Commercial use of my email address NOT allowed. PGP key available. =-



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Re: GRUB vs LILO

[Dvir Oren]

David Woodhouse writes ("Re: GRUB vs LILO "):
> This is because the M-Systems firmware takes up a large chunk of your system 
> RAM for caching block attributes - this is proportional to the size of the 
> DiskOnChip, naturally.

Does Grub already work?

-- 
Dvir Oren               <dviro@lucidvon.com>
Lucid VON Ltd.     <http://www.lucidvon.com>
9 Saloniki St.,        Tel-Aviv       Israel
Tel:  +972 3 644 3038  Fax:  +972 3 644 3039


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Re: GRUB vs LILO

[David Woodhouse]

dvir@hotpop.net said:
>  Does Grub already work? 

Not yet. It detects the DiskOnChip hardware, and scans it until it finds an 
NFTL Media Header. I haven't coded any more than that yet.

--
dwmw2




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Re: Resume from Flash

[John Drabik]

Andreas Kotes wrote:

> I'd like to do resume-from-flash with Linux and DoC 2000, this appears to
> be the fastest possibility to get an embedded system up and running ..
>
> Has anyone done this yet? Any suggestions? Any hints/pointers?

Haven't done it, but I've been looking into it.  There are several issues
and options (at least).

First, you have to decide if you want true resume-from-flash (i.e., the full
state of the system is kept during powerdown).  This is tough, and you'll
need some kind of sleep utility that knows how to save process information,
stack information, etc.  This is easy on the desktop, but a lot more
involved for embedded devices (which is where you'll find Flash - who the
heck is going to pay $75 for a 16 MB Flash disk when they can get a 4 GB HDD
for the same price?)

Alternatively, you could design your system to use fully static design, so
that the clock speed can just be dropped to 0 Hz.  You still have to supply
some power though, and this may not be possible in every situation.  Also,
static RAM and other system components are larger and more expensive than
DRAM.  You need special startup code (not much), and a processor that works
in this way.  Quite a few of the microcontrollers might be candidates, such
as the DragonBall.  But then, you don't get an MMU, and in some cases, you
might not even get the current kernel version (because some of the MMU-less
processor work is lagging).  But this approach is faster than an all-Flash
approach as far as startup, and probably meets your definition of
"resume-in-place".

In either case, you'll need a larger Flash device, because you'll have to
keep the decompressed image in Flash.  Drawbacks?  Larger, more expensive
Flash devices needed, and they're not price-competitive.  You can figure on
about a 100-to-1 premium for the use of DOC devices.

Alternatively, you could decompress from Flash, infrequently, into Static
RAM, and restart only if the Static RAM backup fails.  Issues in this case
include a more complex startup procedure, larger and more expensive Static
RAM array, higher costs, and greater power dissipation.  It isn't clear
whether you'd also need a large Flash device.  My feeling is that copy a
large image from Flash to Static RAM would probably be slower than
decompressing the kernel from the same Flash device to Static RAM, at least,
it is with a "reasonably fast" processor.

Another (easier) choice is to keep the decompressed image in Flash, and
build a new initrd at each boot.  The image doesn't have to decompress, but
you still have to create RAM disk, etc.  This is easier than a purely static
design, or an all-Flash design, in my opinion.  I'm currently thinking of
this as the middle-of-the-road approach.  Reasonably easy, relatively
simple, not too expensive, not too much power dissipation, etc.  It requires
a special loader, but that's about it.  It probably doesn't meet your
criteria for "resume in place" operation though, because the recreation of
initrd means that you are losing state information between reboots or
shutdowns.

Finally, there's the typical approach used today: boot from the Flash device
with a compressed kernel.  Then decompress the image, create the RAM disk,
and go - but then, you don't have that quick startup anymore.

Given the cost of chips such as the 16 MB DOC 2000 (approximately $75 each
in small quantities, at least here in the US), and the cost of a fully
static design (lots more $$$, probably 5- or 10-to-one), it doesn't appear
to make much of a difference; if you want quicker startup, use
execute-in-place, with a decompressed kernel in Flash.

I'm not sure if that answers your questions, but let me know if you'd like
to discuss the matter more.  My guess is that we should take the discussion
off-line, however.

John Drabik




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