ElCondor · Apr 28, 2010 at 09:03 am

Windows Phone 7 Facts: How About ROM Cooking?

This is part 2 of the Windows Phone 7 Facts series. In the following weeks, we will be covering the more technical side of the currently unreleased Windows Phone 7 OS by Microsoft. In the previous article, we were talking about the new installation package called .xap to replace the .cab files.

All information is based on some interesting, XDA-Developers.com exclusive information from XDA member and moderator Da_G. There will be some more changes to the way we were working with Windows Mobile.
One thing that interests most Windows Mobile ‘power’ users, is the ROM.

So will we be still working with the knowm .NBH files when the first HTC WP7 devices come out? The answer is No. Every OEM uses his own design for ROM deployment. HTC uses .nbh files and the RUU system. LG uses .dz/LGMDP files system. No longer this custom design is allowed. There will be standardized  requirements for OEMs for Windows Phone 7 Devices.

So you might be shocked thinking that we would have to develop new kitchens, new tools, etc. Fortunately, the tools we are currently working with will work flawlessly with the new ROM format, B000FF or .bin. The image format will only get some minor changes when compared to CE5 images.

The way the boot loader handles image deployment will change significantly though:

Originally posted by Da_G

For Samsung and a handful of other manufacturers, this (read: ‘image deployment’) won’t change too much, as they already utilize the B000FF system for deployment. The filesystem inside will be IMGFS – no longer will BinFS be used for NK/XIP section (now IMGFS will all partitions on device, NK and OS just being split by package rather than a seperate FS)

Don’t worry if you don’t get this, to summarize: The image deployment of WP7 will be different from older versions of Windows Mobile.

The physical flash layout will look as follows:

  • Reserved Regions, updateable only through a special oem-written driver to allow access to this area (size varies)
  • Partition Table (1KB)
  • BLDR (1MB)
  • DBSP (Device Boot State Partition, 256KB)
  • DPP (Device Provisioning Partition, 256KB)
  • USP (Update State Partition, 2MB)
  • ULDR1 (>=6MB)
  • ULDR2 (>=6MB)
  • NK (read ‘Native Kernel’) (IMGFS, >=4.5MB) – At least 1MB free space for updates
  • OS (IMGFS, >=181MB) – At least 20% free space for updates
  • User Store (TexFAT)

The User Storage are all the files you can explore using a file explorer (For example /Windows, /Program Files, etc.). Thus these files are user-writeable. All other parts are ‘invisible’, and are only writeable during an update operation. The images will be transfered to the bootloader via ethernet over USB. The connection will most likely be encrypted, and probably with the same kind of encryption as the Zune HD. Fortunately the Zune HD has been hacked recently, so let’s hope they’ll be able to hack WP7 too.

There are still some more similarities to CE5 / Windows Mobile 6.x. The BLDR, Base Boot Loader, will not change; OEMs can still choose their own buttons to trigger various actions. The ULDR will still be available for a recovery flash when for instance a power failure shows up:

Similar to CE5/WinMo 6.x, There is a BLDR (Base Boot Loader) which makes the initial determination to boot up to the ULDR or to the WP7 OS. The OEM implements alternate boot parameters to trigger this and/or a button press combination. If ULDR is triggered, it checks the battery and power source to ensure that there is enough life remaining to successfully complete the flash, then awaits the flash download. There are redundant ULDR partitions (ULDR1/ULDR2) to facilitate failsafe recovery in the event of a failed ULDR flash (ULDR provides a basic level of functionality to enable a recovery flash even in the event of power failure during a flash)

As you can see, Microsoft will be very active in trying to get its Phone Update Service the primary method for distributing phone updates. These updates can be deployed over-the-air and through a USB connection using Zune Software.

Concluding, ROM cooking won’t be the problem, only getting the ROMs on your Windows Phone 7 phone will be a real challenge. View the original thread if you have questions or if you want some more information.


_________
Want something on the XDA Portal? Send us a tip!

ElCondor

ElCondor is an editor on XDA-Developers, the largest community for Android users. View ElCondor's posts and articles here.
Jimmy McGee · Apr 28, 2015 at 06:00 am · 2 comments

Xposed Modules to Modify Email – XDA Xposed Tuesday

Even though we have Dropbox and other ways to share files, people still want to send files by email. Some Email apps on your Android device have a limit on file sizes. These limits are often lower that the emails servers limits. Why can’t you attach to the limit set by your server? In this episode of XDA Xposed Tuesday, XDA TV Producer TK reviews a couple Xposed Modules that removed the file size limit of the email client. Today...

XDA NEWS
Emil Kako · Apr 27, 2015 at 12:26 pm · 5 comments

Do You Use 4:3 or 16:9 in the Camera App?

Every person has their own method of taking the best photos on their devices, but which aspect ratio is best when taking photos on your smartphone camera? Let us know whether you prefer to use 4:3 or 16:9 and why in the comments below.

DISCUSS
Aamir Siddiqui · Apr 27, 2015 at 11:12 am · 3 comments

The Curious Case Of The Flash Sale

What do the horses in the Xiaomi stable, notably the Mi 3, Mi 4, Redmi 1S, Redmi 2 & Redmi Note 4G have in common with the YU Yureka or the Micromax Canvas Spark, or even the Lenovo A6000 and the A7000? For starters, the mentioned phones are amongst the more value centric Android smartphones, aiming to offer a better deal in terms of specifications and an overall package, than their domestic and foreign competitors in the Indian market. What...

XDA NEWS
Share This