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-   -   How to raise max partitions number seen by Maemo (https://talk.maemo.org/showthread.php?t=67472)

Fabry 2010-12-26 18:12
How to raise max partitions number seen by Maemo
 
I have repartitioned my eMMC and now I have 10 partitions on it.

Partition managers like sfdisk and parted correctly see all partitions but unfortunately Maemo recognizes only first seven partitions (no /dev/mmcblk0p8, /dev/mmcblk0p9, /dev/mmcblk0p10).

I think it is something related to udev's configuration, but where is the value to change ?

ammyt 2010-12-26 18:35
Re: How to raise max partitions number seen by Maemo
 
10 partitiions! Whoosh why?

Matan 2010-12-26 19:14
Re: How to raise max partitions number seen by Maemo
 
Quote:
Originally Posted by Fabry (Post 904732)
I have repartitioned my eMMC and now I have 10 partitions on it.

Partition managers like sfdisk and parted correctly see all partitions but unfortunately Maemo recognizes only first seven partitions (no /dev/mmcblk0p8, /dev/mmcblk0p9, /dev/mmcblk0p10).

I think it is something related to udev's configuration, but where is the value to change ?
The mmc kernel driver only supports 7 partitions per device. You need to modify this driver in order to use more partitions. This might have compatibility issues, since the block minor number of your /dev/mmcblk0p9 will likely be the same as standard /dev/mmcblk1p1.

Another option is to use dm (device mapper) which can move all partitioning to user space. See kpartx.

Fabry 2010-12-26 19:16
Re: How to raise max partitions number seen by Maemo
 
Quote:
Originally Posted by ammyt (Post 904758)
10 partitiions! Whoosh why?
In physical order they are:
  • /dev/mmcblk0p1 is MyDocs and it is now 10GB
  • /dev/mmcblk0p4 is an extend partition (32KB only)
  • /dev/mmcblk0p5 is a 2GB logical partition (which now contains Nitdroid 0.0.9 manually installed)
  • /dev/mmcblk0p6 is a 2GB logical partition for testing purpose (i.e. reserved for Gingerbread)
  • /dev/mmcblk0p7 is a 4GB logical partition for testing purpose (i.e kubuntu, fedora, ...etc)
  • /dev/mmcblk0p8 is a 4GB logical partition for testing purpose (i.e kubuntu, fedora, ...etc)
  • /dev/mmcblk0p9 is a near 256MB logical partition for u-boot files (kernels, scripts, emergency rescue system, ...etc)
  • /dev/mmcblk0p10 is a 2GB logical partition for testing purpose (i.e. reserved for MeeGo 1.2).
    This partition is here also because in the future I will always be able to delete it and then extend OptFS from 4GB to 6GB
  • /dev/mmcblk0p2 is OptFS and now it is 4GB
  • /dev/mmcblk0p3 is swap area and now it is 1.5GB

Fabry 2010-12-26 19:26
Re: How to raise max partitions number seen by Maemo
 
Quote:
Originally Posted by Matan (Post 904782)
The mmc kernel driver only supports 7 partitions per device. You need to modify this driver in order to use more partitions. This might have compatibility issues, since the block minor number of your /dev/mmcblk0p9 will likely be the same as standard /dev/mmcblk1p1.

Another option is to use dm (device mapper) which can move all partitioning to user space. See kpartx.
I have seen that the problem is still present under MeeGo's kernel.

So since one partition slot is lost by extended partition the max number under N900 is six partitions.:mad:

This is a big problem for my plans:mad:

Fabry 2010-12-27 17:29
Re: How to raise max partitions number seen by Maemo
 
I have changed my partition table to this layout (but I am unhappy for this):
  • /dev/mmcblk0p1 is MyDocs and it is now 10GB
  • /dev/mmcblk0p4 is an extend partition (32KB only)
  • /dev/mmcblk0p5 is a 4GB logical partition (which now contains Nitdroid 0.0.9 manually installed)
  • /dev/mmcblk0p6 is a 8GB logical partition for testing purpose (i.e. kubuntu, fedora, GingerBread...etc)
  • /dev/mmcblk0p7 is a near 2.25GB logical partition for testing purpose (i.e. reserved for MeeGo 1.2)
  • /dev/mmcblk0p2 is OptFS and now it is 4GB
  • /dev/mmcblk0p3 is swap area and now it is 1.5GB

humble 2010-12-27 17:42
Re: How to raise max partitions number seen by Maemo
 
Quote:
Originally Posted by Matan (Post 904782)
Another option is to use dm (device mapper) which can move all partitioning to user space. See kpartx.
or gnu parted (that comes with libdevmapper.so.1.02 too);)

look in my sig

Fabry 2010-12-27 19:18
Re: How to raise max partitions number seen by Maemo
 
Quote:
Originally Posted by humble (Post 905434)
or gnu parted (that comes with libdevmapper.so.1.02 too);)

look in my sig
Yes Parted sees all partitions (I have used it to make them) but then is the kernel that doesn't load a dev node for all partitions with number beyond of 7 so you can't mount them

humble 2010-12-27 19:34
Re: How to raise max partitions number seen by Maemo
 
Quote:
Originally Posted by Fabry (Post 905489)
Yes Parted sees all partitions (I have used it to make them) but then is the kernel that doesn't load a dev node for all partitions with number beyond of 7 so you can't mount them
its good to see we are on the same page. look at what i quoted:) i've have to had read that post:D

Matan 2010-12-27 19:54
Re: How to raise max partitions number seen by Maemo
 
I am afraid you don't understand.

Device mapper is a kernel subsystem that allows creating virtual block devices and mapping them to real devices.

You can for example create a device called /dev/dm9 which is a device of size 4GB starting at 24GB of /dev/mmcblk0. This way, even if you don't have an mmc block device for this partition, you can still use it.

kpartx is a tool that automates this. You point it to a block device, and it creates a dm device for each partition on the device, regardless of partition number limitations of the underlying block device driver.

Fabry 2010-12-27 21:51
Re: How to raise max partitions number seen by Maemo
 
Quote:
Originally Posted by Matan (Post 905512)
I am afraid you don't understand.

Device mapper is a kernel subsystem that allows creating virtual block devices and mapping them to real devices.

You can for example create a device called /dev/dm9 which is a device of size 4GB starting at 24GB of /dev/mmcblk0. This way, even if you don't have an mmc block device for this partition, you can still use it.

kpartx is a tool that automates this. You point it to a block device, and it creates a dm device for each partition on the device, regardless of partition number limitations of the underlying block device driver.
Yeah I had figured I could use a DM device and with "you can't mount them" I meant "through MMC device"

Unfortunately device mapper add an extra layer of complexity that i prefer to avoid.

kpartx exists compiled for N900 ?

Can I boot from dm device ?
Response is yes, but on Maemo (power kernel) dm device is a external module so I need an initrd or a custom kernel with dm device embedded to boot from a dm device

When I want to boot an alternative os (like Nitdroid, Kubuntu, ...etc), others problems will appear ?

U-Boot can see these partitions (i.e for loading a kernel from mmcblk0p8) ?

humble 2010-12-27 23:53
Re: How to raise max partitions number seen by Maemo
 
1 Attachment(s)
kpartx needs more than device mapper lib's, it needs as Matan stated device mapper(driver) a la kernal.
Edit: im using power46

Matan 2010-12-28 12:44
Re: How to raise max partitions number seen by Maemo
 
Did you try

modprobe dm-mod

humble 2010-12-28 22:42
Re: How to raise max partitions number seen by Maemo
 
Quote:
Originally Posted by Matan (Post 905962)
Did you try

modprobe dm-mod
that worked:)


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