Stock ROM v. 3.06.708.3 for HTC Butterfly S

Making of the installer

The first complication appeared while I was trying to apply the OTA update to a stock, unmodded system on the previous version. I installed the stock recovery from the previous update and let it install the OTA. It rebooted and... got stuck while booting the system. Weird colors on the screen and it just hung.

So I tried again, but this time I selected the update ZIP manually in the recovery in order to see the messages it prints. It failed on set_metadata_recursive -- it was trying to set extended capabilities and SELinux labels on certain files. The stock recovery from 2.21.708.1, however, doesn't support these kinds of metadata. Solution? Install the recovery from the update I was trying to apply and try again -- went just fine.

I have no idea how the update is supposed to work on locked unmodded phones, but whatever. Or maybe I just installed an older version of the recovery by mistake... No idea and I'm not curious enough to investigate this further.

Making the ZIP installer was another challenge. At first, I just took the installer from 2.21.708.1, replaced the files, updated the description, copied additional metadata commands from the OTA installer, built the package and tried to install.

It failed, of course.

The problem was that I was using an update-binary I found somewhere on the XDA forums (don't recall where) and it looks like it is some old version which doesn't support the new set_metadata and set_metadata_recursive functions. The easiest thing for me to do was to just take the update-binary from the official OTA package.

This, however, broke the installation of boot.img. Butterfly S doesn't have any MTD partitions, its storage is accessed as EMMC. The problem is, in the upstream version of the installer, write_raw_image can only write images to MTD partitions, not EMMC. The old version of the binary I was using previously must have been patched to support EMMC as well.

Luckily, just calling dd to write the image to /dev/block/mmcblk0p36, which is the boot partition on the Butterfly S, seems to work fine.

The only remaining problem is that none of the builds of TWRP that are available at the moment support filesystem capabilities and SELinux labels, which means the set_metadata calls will fail when trying to set them. From what I've read, only CWM Touch 6.0.4.5 is recent enough to support the metadata, but the only build available doesn't support the external SD.

I could always make two versions of the ROM, one for recoveries with support for these kinds of metadata and one for recoveries without the support, but I'm not a big fan of that. Instead, I modified the installer to first set the regular metadata that works everywhere and only try to set the extended metadata as the very last step of the installation process.

If the metadata isn't supported, it should be OK, the installation will fail, but everything should be safely in place at that point. If it is supported, there's no problem at all. Either way, you end up with a working stock system, only the installer might fail, but you can safely ignore that.

So yeah, that's a short version of the story; in reality, it took me a lot more attempts to flesh out stupid mistakes but these were the biggest issues I encountered. Consider that it takes about 15 minutes to build the ZIP and push it to the device and then I had to wait for it to finish unpacking just to see where it failed... Well, it was tedious.

My impressions of the 4.4.2 system

I've been using the new system for about a day and a half and my impressions are mixed so far.

The nicest feature I noticed about the update is the ability to bring up the notification bar even in full-screen apps. It also turns some of the notification area icons (notably, the battery indicator) to black-and-white which is okay, I guess; it makes the overall look somewhat more consistent with the general monochromatic theme.

However, a big issue seems to be the battery drain. After I finished tuning the ROM installer, my phone was most certainly fully charged. Within 11 hours of medium usage, the battery level was down to about 10%, which is much worse than on my old HTC Desire after three years of service with the original battery.

Today, it appears to have performed a tiny bit better, after a full day it is at 32%. I guess I'll try to give the system a week to settle (I know the Android system needs some time to make statistics in order to optimize memory and process management), but if things don't improve significantly, I'm afraid I'll have to revert back to 4.3.