Application for bridging SDHC as device memory [Archive]

Chef_Tony

4th August 2009, 11:50 AM

maybe this is not about ram but about having the sd card as primary partition, which might be possible although it has never been done before. in wm2003 the ramdrive was the primary partition and the "storage" was listed as a storage card. these days the storage is the first (and on most devices and roms only) partition. but when a ramdisk is added, it is listed as a storage card. that means the order of the drives is variable and a storage card could also be the first partition.

but what would you want with a theretical answer like that? an expert rom chef, who started with cooking wm2003 might know the answer or could do that for you.

but for all realistic means, you should simply try and save all documents, pictures, videos and music, install bigger programs, derive the cache for your browser, store email attachments all on the sd card. the only problems with completely leaving out on the internal storage, especially for program installation, is that it is slow.

TFGBD

26th August 2009, 02:12 AM

It should be possible but you will probably need to cook a new ROM to get it working. It's mostly just a matter of telling CE which mounted volume you want to mount as root for the emulated objectstore.

This document on MSDN should give you an idea of what to do:
http://msdn.microsoft.com/en-us/library/ms885839.aspx

The MPx200's WM5/WM6 ROMs do this already. If you do this, keep in mind you likely won't ever be able to eject the card while the device is booted as the registry will be stored there. Now, maybe you could write some sort of app that would dismount/remount and reinitialize the registry at the press of a button but that doesn't seem too practical unless you have no choice as on the MPx200. Another workaround might be to store the registry hives on an internal flash partition and store the rest of the system folders on the SD card.

As for implementing the RAM/ROM based filesystem like in WM2003, I'm not sure. The Windows CE 5.x kernel used for Windows Mobile 5/6/6.1/6.5 certainly won't prevent you from doing it but I'm unsure the Universal's hardware can persist the ram contents between "soft" resets. If it can, then I imagine it's only a matter of using an NK.exe that doesn't force a clean reboot and using a different filesys.exe than the included ROM only/hive registry configuration it ships with. Heh, if you ever looked at the MS news groups you will see a whole bunch of posts by OEMS getting yelled at for using the ram based configuration in their beta WM5 roms. "Not supported" doesn't mean it can't be done and work, it just means MS doesnt' want you to do it for either marketing or other reasons.

maybe this is not about ram but about having the sd card as primary partition, which might be possible although it has never been done before. in wm2003 the ramdrive was the primary partition and the "storage" was listed as a storage card. these days the storage is the first (and on most devices and roms only) partition. but when a ramdisk is added, it is listed as a storage card. that means the order of the drives is variable and a storage card could also be the first partition.

but what would you want with a theretical answer like that? an expert rom chef, who started with cooking wm2003 might know the answer or could do that for you.

...

The ramdisk you are talking about is very different from the Windows CE object store used in WM2003 and many current non-PPC WinCE devices.

They don't even use the same filesystem! The ramdisk driver commonly circulated on these forums basically just formats/mounts a chunk of RAM as a FAT partition. It can't be resized and appears to the OS as any other flash card. You can even format it with StorageTools or whatever. The dynamic ramdisk or objectstore is built into the WinCE OS. It uses a proprietary filesystem optimized for RAM usage that is closely integrated into the kernel. As I understand it, It's more like a database than a filesystem like FAT. The registry, files and DBs are all stored in the same internal format and then abstracted by the OS and it's APIs. It couldn't even be disabled until more recent WinCE versions. More info: http://msdn.microsoft.com/en-us/library/aa910544.aspx