[U-Boot] [PATCH 3/4] sunxi: Add default partition scheme

[Andre Przywara]

Hi,

On 15/11/17 21:03, Alexander Graf wrote:
> 
> 
> On 15.11.17 11:11, Maxime Ripard wrote:
>> The partitions variable is especially useful to create a partition table
>> from U-Boot, either directly from the U-Boot shell, or through flashing
>> tools like fastboot and its oem format command.
>>
>> This is especially useful on devices with an eMMC you can't take out to
>> flash from another system, and booting a Linux system first to flash our
>> system then is not really practical.
>>
>> Signed-off-by: Maxime Ripard <maxime.ripard at free-electrons.com>
>> ---
>>  include/configs/sunxi-common.h | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/include/configs/sunxi-common.h b/include/configs/sunxi-common.h
>> index 4391a8cbc824..11da6ccfbf54 100644
>> --- a/include/configs/sunxi-common.h
>> +++ b/include/configs/sunxi-common.h
>> @@ -493,6 +493,12 @@ extern int soft_i2c_gpio_scl;
>>  #define SUNXI_MTDPARTS_DEFAULT
>>  #endif
>>  
>> +#define PARTS_DEFAULT \
>> +	"name=loader1,start=8k,size=32k;" \
>> +	"name=loader2,size=984k;" \
>> +	"name=boot,size=128M,bootable;" \
>> +	"name=system,size=-;"
> 
> Is there a particular reason you're creating a boot and system
> partition? In a normal distro world, the distro installer will take care
> of creating ESP + root + swap + whatever for you - and they (or the user
> driving the installation) usually know best what they need :)

But do we actually care about this? If I understand this correctly,
these are default settings for U-Boot's "mtdparts default" command,
which honestly I didn't even know existed so far.
So in a distribution scenario I wouldn't expect somebody to actually use
this. Instead you boot from a (possibly unpartitioned) SD card with just
U-Boot on it or from SPI flash, then launch an installer from somewhere
(PXE, USB drive) and let it do its job. No U-Boot partition involved.
And even if you use mtdpart, you can always override these default
settings on the command line.

Does mtdparts even use partition tables (MBR/GPT)? mtd sounds quite
Android-y/embedded to me (passing partition information via command line).

So apart from that I think it's good to have a default FAT/ESP
partition, also for storing the environment.

It's debatable whether we need a system partition defined at this stage.
Can't this just left be unpartitioned, to be actually populated later?
In a MBR/GPT scenario I would expect a big partition covering the whole
device causes headache later on.

Cheers,
Andre.