[U-Boot-Users] decrease boot time

[Konstantin Kletschke]

Am 2005-02-12 14:02 -0700 schrieb Grant Likely:
> 
> Please make sure that you include the mailing list when you reply to me.

Oh sorry! I messed up List-Reply and simple Reply again in mutt.
Normally I only reply to the mailing list itself :/

> You think?  If possible; I would get some hard numbers on your boot
> sequence and find out for sure.  You could use a serial protocol
> analyser to attach timestamps to the boot logs.  Make sure you're
> optimizing the right things.

Yes, its time now to measure all steps of the boot process exactly.
The serial analyzer idea is quite good. Why isn't it mine :)

> arch/arm/boot/compressed/head.S.  You will see a branch to cache_on at
> line 287 before decompress_kernel at line 310.  (2.6.10)  According to
> the comment on line 422 the page tables are setup for wherever the
> compressed image is; including if it is in FLASH.

Yes I see. But I don't understand the assembler code really yet. Do you
mean "add     r0, r3, r2, lsl #2" by line 422, where addresses above
0x10040000 (there my kernel lives) are added to cacheable area?

> To u-boot prompt or to linux prompt?

To linux prompt. I heard from a sony demo where an ARM9 based system
starts video encoding one second after power up. I asked in
linux-arm-kernel last year and some guy mentioned that.
So I thought I could reach the prompt also in one second :/

> > > safe to assume that you've got a 'boot loader' flash device with a
> > > small first (~16k)?
> > 
> > What do you mean by that?
> I mean that some flash devices have some small sectors at the
> beginning specifically to hold the boot loader.  If you were trying to
> save space I wondered if you were trying to fit into a small sector. 
> This is often done when FLASH space is at an extreme premium.

No I have intel 28F128K3 sync burst Flash which contains even sized
128kB sectors only.

> Linux can spew a lot of log messages; I suspect your time difference
> would be more bounded by the baud rate of the port rather than the
> serial device driver itself.  U-boot on the other had is quite a bit

T thought also and measured and my result is the same.

> Can you bump up your baud rate?

It is at 115200 now, I could bump it but I don't think it will to
significant time saving due to the above reasons...

Konsti

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