[U-Boot] [PATCH] OMAP4: speed up booting on Pandaboard

[Nishanth Menon <menon.nishanth@gmail.com>]

Sergiy Kibrik wrote, on 11/05/2010 08:35 AM:
> On 11/04/2010 05:46 PM, Nishanth Menon wrote:
>> Sergiy Kibrik wrote, on 11/04/2010 05:38 AM:
>>> Improved default config for OMAP4 Pandaboard for faster boot:
>>>      -reduced environment size to speed up memory initialization;
>>>      -USB TTY driver turned off;
>> Do we really want to do this?
>
> well, Pandaboard has serial port. It can be used instead of usbtty
how about all those folks who dont have a serial cable handy instead 
would like to power the board + see the terminal over usb?

>
>>>      -tweaked blob load address to avoid image relocation (according to
>>> default uImage load address);
>>>
>>> Signed-off-by: Sergiy Kibrik<sergiy.kibrik@globallogic.com>
>> What kind of savings did we get? I am guessing we have some time x
>> savings..
>>
>
> reducing ENV_SIZE saves ~0.2 s.
> turning off usbtty saves ~0.2 s.
> changing loadaddr saves about a second. As shown my measurements, all introduced changes save
 > about 1.3 - 1.5 seconds.
for what? getting to u-boot shell prompt? if so, I wonder how it does it 
actually happen.

>
>>> ---
>>>    include/configs/omap4_panda.h |    8 ++++----
>>>    1 files changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/include/configs/omap4_panda.h
>>> b/include/configs/omap4_panda.h
>>> index 74defab..5aba424 100644
>>> --- a/include/configs/omap4_panda.h
>>> +++ b/include/configs/omap4_panda.h
>>> @@ -62,10 +62,10 @@
>>>
>>>    /*
>>>     * Size of malloc() pool
>>> - * Total Size Environment - 256k
>>> + * Total Size Environment - 2k
>>>     * Malloc - add 256k
>>>     */
>>> -#define CONFIG_ENV_SIZE            (256<<   10)
>>> +#define CONFIG_ENV_SIZE            (256<<   4)
>> /me likes the change, but not sure how it saves boot time.
>
> again, it's about 0.2 seconds

surprised how changing env saves 0.2 seconds - apologies, I dont have a 
panda on hand at the moment to do some actual tests with the board and 
patch :(

>
>>
>>>    #define CONFIG_SYS_MALLOC_LEN        (CONFIG_ENV_SIZE + (256<<   10))
>>>                            /* initial data */
>>>    /* Vector Base */
>>> @@ -117,7 +117,7 @@
>>>
>>>    /* USB device configuration */
>>>    #define CONFIG_USB_DEVICE        1
>>> -#define CONFIG_USB_TTY            1
>>> +#undef CONFIG_USB_TTY
>> do we need to have the undef? it might be better to just drop the define
>> perhaps? what impact do we have on boot time with this change?
>
> if someone wants to turn usbtty again, he can simply #define variable again,
 > in case we drop the whole line it may be slightly harder to find out 
proper
 > variable in the code and then #define it all over again. I just thought
 >keeping it will clarify config in some way.

adding a comment will help
/* enable this to get tty over usb */
>>
>>>    #define CONFIG_SYS_CONSOLE_IS_IN_ENV    1
>>>
>>>    /* Flash */
>>> @@ -146,7 +146,7 @@
>>>    #define CONFIG_ENV_OVERWRITE
>>>
>>>    #define CONFIG_EXTRA_ENV_SETTINGS \
>>> -    "loadaddr=0x82000000\0" \
>>> +    "loadaddr=0x80007FC0\0" \
>> btw, Dumb question: how did we decide on this address? building from
>> kernel.org, I see System.map @ c0004000 ==>  80004000
>>
>> when I do make uImage,
>> /bin/bash /home/nmenon/Src/opensource/linux-2.6/scripts/mkuboot.sh -A
>> arm -O linux -T kernel -C none -a 0x80008000 -e 0x80008000 -n
>> 'Linux-2.6.37-rc1-00005-gd88c092'
>>
> 0x80007FC0 is kernel load address (0x80008000) minus size of u-boot header (64 bytes). So load address is exactly the same as image address inside loaded blob, and we avoid memmoving kernel to it's load address.
thanks for the clarification -> it might be good for us to come up with 
something a bit more automated as you can, in theory run mkuboot.sh with 
a different address.

-- 
Regards,
Nishanth Menon