Just visited the XDA developer website forums and found that a custom ROM for Galaxy Tab P1000 already available. The CyanogenMod 11.0 custom ROM, built and compiled by terenceng, I just downloaded the ROM and flashed to my Galaxy Tab P1000 via CWM Recovery.
UPDATE: There is unofficial release of CyanogenMod 13 which is based-on Android 6.0 Marshmallow available to download. You can follow our tutorial on how to install CyanogenMod 13 on Galaxy Tab P1000.
The ROM flashed successfully smoothly. According to the forum post, it should have all the features mentioned there however in the result the very important thing, Mobile Networks, is not there…dohh!! It is missing, so my GT-P1000 flashed with this ROM is not capable to send SMS, phone call, 3G data and other mobile network-related tasks. It is confirmed that other users also experiencing the same issue that no mobile networks on this ROM. The latest build now supports Mobile networks (sms/call, data services). See the update below!
UPDATE!!! 27 Nov 2013 – the developer just released a new version cm-11-20131127-terenceng-p1.zip which supports Mobile networks feature. I have tested send/receive SMS, make/receive call, and Data services (3G/HSDPA), it is working well so far. You must upgrade to this version if you are already in the CM 11.
5 Dec 2013 – the developer released a new version cm-11-20131205-terenceng-p1.zip which works almost perfect. In the new build Screenshot now working (Enable screenshot: Settings > Buttons > Power menu > Screenshot. To take screenshot: hold Power button and tap Screenshot). Switching between portrait and landscape mode are now also smooth. Since Google Play is removed in this build, you need to download and install Google Apps manually. You can download the Google Apps packages from here (Banks GApps).
7 Dec 2013 – Official CyanogenMod 11 nightly build for Galaxy Tab GT-P1000 is available for download from CyanogenMod website. It is based-on Android 4.4.1 KitKat which comes with several bug fixes. WhatsApp application now runs on ART mode on this build. You still need to download and install separately/manually the Google Apps (Banks GApps 4.4.1 works well).
The Wifi is running perfectly. I tried to install some popular apps such as Facebook, Google+, Twitter, Skype, Yahoo Messenger, Google Chrome, Google Maps, GMail, YouTube and WhatsApp Messenger. They are working without any problems. However, one of my favourite app, Google+, is not available. It said that ‘Your device isn’t compatible with this version‘ when I tried to install Google+ app. Google+ now running well on this build.
If you want to try download and install this ROM, the download link can be found in the forum post above.
Watch the video below on how to install Android 4.4 KitKat on Galaxy Tab P1000.
Using CWM (ClockworkMod)
Using TWRP (Team Win Recovery Project)