[Gta04-owner] QtMoko v49

EdorFaus edorfaus at xepher.net
Thu Nov 22 01:44:59 CET 2012


On 11/19/2012 11:19 AM, Paweł Więcek wrote:
> On Mon, 2012-11-19 at 11:07 +0100, Radek Polak wrote:
>> p1 - FAT partition with uImage so that the current initramfs can work without
>> changes
>>
>> p2..p4 rootfs for QtMoko, SHR whatever
>>
>> p5 - FAT for media
>> p6 - swap
>
> But this is not possible.

I noticed this too, and thought I'd explain why.

[Edit: in retrospect, after writing the below, I realized you might have 
been numbering the partitions logically, instead of by position like 
Linux does. If so, the below is still true except that it doesn't really 
apply for the possibility of the above scheme (assuming the boot loader 
can boot from extended partitions).]

The reason this is not possible, is because one of p1..p4 is used up by 
the extended partition that contains the remaining partitions (as the 
primary table only has room for 4, and we have to know where to find the 
rest).

Normally this would be the first of p1..p4 that is not otherwise used 
(it *might* be possible to always use p4 for this even if p3 is not 
used... but I'm not sure about that).

The extended partition, in turn, has another table that technically has 
room for up to four further partitions - but IIRC most partitioning 
tools only use the first entry for an actual data partition, and (if 
there are more partitions on the disk) set the second entry to another 
extended partition, which follows the same format.

I don't know if there's a reason to do it that way other than ease of 
implementation, or if most/any OSes support reading extended partitions 
with more than one data partition per table, so it might be possible to 
get away with just one as long as we don't need more than 7 partitions.

-Frode


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