AT91SAM9G20 design and boot times

AT91SAM9G20 design and boot times

[Aras Vaichas]

Hi,

we're designing our next generation RFID reader and I'm planning on
using the AT91SAM9G20 in the next design. We currently use the
AT91RM9200.

Can I get some feedback from people with regards to general design
configurations  that affect the boot time with respect to this CPU (or
the AT91SAM9260)

Some questions are:

* what is your boot time? What is the time from power-on to kernel
running, how long does the kernel take to run until init starts, and
how long does init take?
* what is your system hardware configuration? CPU+NAND, CPU+NOR+NAND,
CPU+DATAFLASH+NAND?
* do you boot everything from the NAND or do you use a combination of
Dataflash/NOR and NAND?
* do you use U-Boot, or a minimal custom bootloader that copies a
kernel image from NAND to SDRAM and then executes it?
* do you mount a small partition of the NAND to begin with and then
mount the rest later?
* do you have a monolithic kernel, or is it split into minimal with
modules loaded from, say, JFFS2 on NAND?
* are you using JFFS2 or UBIFS?

Any info is much appreciated, thank you!

regards,

Aras Vaichas

Re: AT91SAM9G20 design and boot times

[Nicolas Ferre]

Hi,

Aras Vaichas :
> Hi,
> 
> we're designing our next generation RFID reader and I'm planning on
> using the AT91SAM9G20 in the next design. We currently use the
> AT91RM9200.

Good choice ;-)

> Can I get some feedback from people with regards to general design
> configurations  that affect the boot time with respect to this CPU (or
> the AT91SAM9260)

I presume that you already know what are the configurations we are using
at Linux4sam.org on our at91sam9g20ek board. Anyway, I answer your
questions as it may also interest other readers.

> Some questions are:
> 
> * what is your boot time? What is the time from power-on to kernel
> running, how long does the kernel take to run until init starts, and
> how long does init take?

We have not tried to be clever on speeding up boot process but I guess
that we can save time:
- removing unneeded bootloader steps (remove u-boot for instance)
- removing unused drivers
- lower timeouts (Ethernet phy detection for example)
- tailor rootfs exactly to your needs

That said, here are numbers from our not optimized demo
(AT91Bootstrap+u-boot+linux+buildroot):
- ~6s to Linux (can certainly be optimized)
- ~+2s to init
- ~+5s to login (here also)

> * what is your system hardware configuration? CPU+NAND, CPU+NOR+NAND,
> CPU+DATAFLASH+NAND?

CPU + NAND can lower your BOM

> * do you boot everything from the NAND or do you use a combination of
> Dataflash/NOR and NAND?

Both.

> * do you use U-Boot, or a minimal custom bootloader that copies a
> kernel image from NAND to SDRAM and then executes it?

If boot time is a hot topic, choose AT91Bootstrap that directly loads Linux.

> * do you mount a small partition of the NAND to begin with and then
> mount the rest later?

With JFFS2, I advice you to tailor your NAND partition for rootfs to the
minimum. You will then have room in another partition once your system
is up-n-running.

> * do you have a monolithic kernel, or is it split into minimal with
> modules loaded from, say, JFFS2 on NAND?

Monolithic kernel.

> * are you using JFFS2 or UBIFS?

JFFS2 for the moment. We will certainly consider moving to UBIFS.

Bye,
-- 
Nicolas Ferre

Re: AT91SAM9G20 design and boot times

[Robin Getz]

On Thu 11 Jun 2009 08:48, Nicolas Ferre pondered:
> Aras Vaichas :
> > * what is your boot time? What is the time from power-on to kernel
> > running, how long does the kernel take to run until init starts, and
> > how long does init take?

[snip]

> That said, here are numbers from our not optimized demo
> (AT91Bootstrap+u-boot+linux+buildroot):
> - ~6s to Linux (can certainly be optimized)
> - ~+2s to init
> - ~+5s to login (here also)

Holy long boot times batman.

For a sub 1 second (973ms) boot (to userspace - end of the /etc/rc file), have 
a look at:

https://docs.blackfin.uclinux.org/doku.php?id=fast_boot_example

It also includes a 421ms for a minimal kernel.

No magic - just careful optimisation of the BootROM, U-Boot, and the kernel.

Some of the tricks we do are architecture independent, and should be able to 
be applied to any system. Your milage may vary - depending on your 
distribution, and your architecture.

-Robin

Re: AT91SAM9G20 design and boot times

[Jean-Christophe PLAGNIOL-VILLARD]

On 14:48 Thu 11 Jun     , Nicolas Ferre wrote:
> Hi,
> 
> Aras Vaichas :
> > Hi,
> > 
> > we're designing our next generation RFID reader and I'm planning on
> > using the AT91SAM9G20 in the next design. We currently use the
> > AT91RM9200.
> 
> Good choice ;-)
> 
> > Can I get some feedback from people with regards to general design
> > configurations  that affect the boot time with respect to this CPU (or
> > the AT91SAM9260)
> 
> I presume that you already know what are the configurations we are using
> at Linux4sam.org on our at91sam9g20ek board. Anyway, I answer your
> questions as it may also interest other readers.
> 
> > Some questions are:
> > 
> > * what is your boot time? What is the time from power-on to kernel
> > running, how long does the kernel take to run until init starts, and
> > how long does init take?
> 
> We have not tried to be clever on speeding up boot process but I guess
> that we can save time:
> - removing unneeded bootloader steps (remove u-boot for instance)
> - removing unused drivers
> - lower timeouts (Ethernet phy detection for example)
> - tailor rootfs exactly to your needs
> 
> That said, here are numbers from our not optimized demo
> (AT91Bootstrap+u-boot+linux+buildroot):
> - ~6s to Linux (can certainly be optimized)
> - ~+2s to init
> - ~+5s to login (here also)
I've done some test on 9263
with the following config
cpu+nor (u-boot+linux+busybox)
~4/5s to the prompt

if the boottime is critical I'll recommend you NOR + XIP

> 
> > * what is your system hardware configuration? CPU+NAND, CPU+NOR+NAND,
> > CPU+DATAFLASH+NAND?
> 
> CPU + NAND can lower your BOM
> 
> > * do you boot everything from the NAND or do you use a combination of
> > Dataflash/NOR and NAND?
I've test it on 9263
> 
> Both.
> 
> > * do you use U-Boot, or a minimal custom bootloader that copies a
> > kernel image from NAND to SDRAM and then executes it?
> 
> If boot time is a hot topic, choose AT91Bootstrap that directly loads Linux.
I disagree on this because you will loose a lot's of possibity as bootcount
DFU, store your kernel in your rootfs etc...

> 
> > * do you mount a small partition of the NAND to begin with and then
> > mount the rest later?
> 
I'll consider to switch to UBIFS
and use lzma compression (for the uImage) if no XIP

Best Regards,
J.

Re: AT91SAM9G20 design and power (was and boot times)

[Christian Gagneraud]

Aras Vaichas wrote:
> Hi,
> 
> we're designing our next generation RFID reader and I'm planning on
> using the AT91SAM9G20 in the next design. We currently use the
> AT91RM9200.
> 
> Can I get some feedback from people with regards to general design
> configurations  that affect the boot time with respect to this CPU (or
> the AT91SAM9260)
> 
> Some questions are:
> 
> * what is your boot time? What is the time from power-on to kernel
> running, how long does the kernel take to run until init starts, and
> how long does init take?
> * what is your system hardware configuration? CPU+NAND, CPU+NOR+NAND,
> CPU+DATAFLASH+NAND?
> * do you boot everything from the NAND or do you use a combination of
> Dataflash/NOR and NAND?
> * do you use U-Boot, or a minimal custom bootloader that copies a
> kernel image from NAND to SDRAM and then executes it?
> * do you mount a small partition of the NAND to begin with and then
> mount the rest later?
> * do you have a monolithic kernel, or is it split into minimal with
> modules loaded from, say, JFFS2 on NAND?
> * are you using JFFS2 or UBIFS?
> 
> Any info is much appreciated, thank you!

Hi all,

I'm changing slightly the topic...

We are thinking about making our own board as well, but we are mainly 
concerned with power consumption.

Can anyone gives some feedback as well about power consumption of 
their board (or the main components) and as well about the current 
support for power management of the Linux kernel? What about suspend 
to RAM, frequency scaling, etc...?

Regards,
Chris

> 
> regards,
> 
> Aras Vaichas
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Re: AT91SAM9G20 design and boot times

[Marc Pignat]

Hi all!

> if the boottime is critical I'll recommend you NOR + XIP
Nak, please have a look at "interest in XIP? - boot time benchmarks"
(http://marc.info/?l=linux-arm-kernel&m=117198517723134&w=2)

But in brief : the kernel is started faster with xip, but is so slow that it
will end booting after the non-xip kernel.

NOR flash bandwidth is *very* slow compared to SDRAM.

Best regards

Marc