Does anyone know how HHL boots?

Does anyone know how HHL boots?

[Matthew Dharm]

I'm somewhat curious...

MontaVista has HHL support for several MIPS boards... including one that my
company makes.  We've never actually seen their HHL distribution for our
board, tho... and we're wondering, how does it boot?

I mean, our boards have an elementary boot loader that can load a kernel
from the network, and disk-booting is something we're trying to figure out.
But how does HHL accomplish this?  And is it a general solution for
multiple platforms?

Matt

-- 
Matthew Dharm                              Work: mdharm@momenco.com
Senior Software Designer, Momentum Computer

Re: Does anyone know how HHL boots?

[Geoffrey Espin]

Matt,

> MontaVista has HHL support for several MIPS boards... including one that my
>... 
> I mean, our boards have an elementary boot loader that can load a kernel
> from the network, and disk-booting is something we're trying to figure out.
> But how does HHL accomplish this?  And is it a general solution for
> multiple platforms?

I went thru the same pain and confusion myself 9 months ago.  My
understanding is MontaVista uses whatever the manufacturer supplies
with the hardware.  And/or they have an internal version of PMON.
There are probably a dozen differernt MIPS loaders... some of
which you might be able to find source for, but probably won't
be even close to working on your board without weeks+ of effort.

If you have some assembly startup code that turns off interrupts,
sets up the memory controller then you maybe able to use my "LinuxMon"
solution which only works on the Korva(Markham) NEC Vr41xx chip
but is very generic.  Sheese, every monitor says it's generic.
After turning off interrupts and setting up the memory controller
it copies (optionally gunzips) the remainder of flash then jumps
to your linux kernel.  A 1-stage boot.  It can then be used
to load a second linux kernel if it has been linked elsewhere.

I wasn't successful in getting it submitted/accepted unfortunately.

You can get a copy of my 2.4.16 release containing it, at:

    http://www.idiom.com/~espin/nec

The important files are arch/mips/korva/{Boot.make,vrboot.S,misc.c}
If you have an already working linux kernel then these few files
should turn it into a boot monitor.  These were posted to
linux-mips-kernel@lists.sourceforge.net so you can find them in
the mail archive in Nov/Dec.  Or I can post.

Geoff
-- 
Geoffrey Espin
espin@idiom.com

Re: Does anyone know how HHL boots?

[Pete Popov]

On Thu, 2002-01-24 at 01:50, Matthew Dharm wrote:
> I'm somewhat curious...
> 
> MontaVista has HHL support for several MIPS boards... including one that my
> company makes.  We've never actually seen their HHL distribution for our
> board, tho... and we're wondering, how does it boot?
> 
> I mean, our boards have an elementary boot loader that can load a kernel
> from the network, and disk-booting is something we're trying to figure out.
> But how does HHL accomplish this?  And is it a general solution for
> multiple platforms?

HHL, or now MontaVista Linux, MVL, is a cross dev environment. The tools
and all apps are installed on the host system. The target boots over the
net, which requires that the boot code support net booting, and then
mounts the root fs over nfs.  You can then proceed to develop your apps
on the host system, install it in the target directory, test it, etc.
When you're ready for deployment, you can use the Target Configurator
Tool to build a custom file system. 

How you deploy the system varies.  I'll give you an example of a board
I'm working on right now.  The Pb1500 from Alchemy has yamon as the boot
code. I've added boot from flash support so you can compile a zImage
kernel. The image is then turned to srecords, which yamon can download
directly to flash (if the srecords' addresses are those of the flash).
You can then set a "start" variable in yamon which is a string that
yamon parses, such as: "go bfd00000 root=/dev/mtdblock0". Assuming that
you have the zImage at 0xbfd00000, yamon will just jump there and the
kernel loader that's part of the zImage will do the rest. The root file
system, in this case, is in flash. This means that you need mtd and jffs
or jffs2 support. Another option for this board is to put the root fs on
a pcmcia card or on a hard disk, since the board has the HPT370A IDE
controller.  I've tested both.

I guess the short answer is that MVL boots over the network and mounts
the root fs over nfs.  For deployment, it depends on what you need or
what your customers need.  It also depends on the features of your boot
code and the level of support for your board in the kernel tree (mtd,
jffs, etc).  It might be very easy to deploy the board, or you might
have to either pay someone PS or add the additional features you need
yourself.

Pete

Re: Does anyone know how HHL boots?

[Pete Popov]

On Thu, 2002-01-24 at 08:37, Geoffrey Espin wrote:
> Matt,
> 
> > MontaVista has HHL support for several MIPS boards... including one that my
> >... 
> > I mean, our boards have an elementary boot loader that can load a kernel
> > from the network, and disk-booting is something we're trying to figure out.
> > But how does HHL accomplish this?  And is it a general solution for
> > multiple platforms?
> 
> I went thru the same pain and confusion myself 9 months ago.  My
> understanding is MontaVista uses whatever the manufacturer supplies
> with the hardware.  And/or they have an internal version of PMON.
> There are probably a dozen differernt MIPS loaders... some of
> which you might be able to find source for, but probably won't
> be even close to working on your board without weeks+ of effort.

There is pmon2000 which was ported to mips and runs on the ev96100
(rm7k). Porting it to the Ocelot should be straight forward. The CPU is
the same. The system controller is different, but the gt96100 is a
superset of the gt64120, so that part should be easy too. I believe the
low level code that initializes the memory controller will be the same.
I did find a bug in the mem init code that reports the wrong memory size
and sets up the sub decoder incorrectly, but ... it still worked and I
didn't have time to fix it.

Pmon2000 is rather large because it's openbsd based. What's nice though
is that porting drivers to it is much easier since you can just grab it
from openbsd and get rid of some of the memory/bus code.

Another option I like a lot is yamon from MIPS T.  I don't know how long
it would take to port it to the rm7k and the gt64120, but it can't be
that bad.  

Pete

Re: Does anyone know how HHL boots?

[Jun Sun]

Matthew Dharm wrote:
> 
> I'm somewhat curious...
> 
> MontaVista has HHL support for several MIPS boards... including one that my
> company makes. 

I suppose you are referring to Ocelot.  It is supported in HHL2.0.

> We've never actually seen their HHL distribution for our
> board, tho...

Strange.  You should get one set of CD's.  I am not sure about the business
arrangment.  Please contact support@mvista.com.

> and we're wondering, how does it boot?

Kernel is booted through netboot.  Root fs is NFS.  It is documented in the
CD's.

Jun