GPS accuracy - why so different ? - Android Q&A, Help & Troubleshooting

Hi !
Does somebody know what is the reason for GPS accuracy being so different between stock, official and custom ROMs ?
In case of my devices (mostly Lenovo) it is so that when running stock ROMs their GPS module has 3m accuracy.
Then after I flashed custom ROMs, it goes down as low as 1m. That's quite a difference !
Why is it so ?

That is the difference between drivers made for the device and open source drivers. Open source files are never as good as the closed sourced versions. It is something you accept when you use custom roms.

zelendel said:
That is the difference between drivers made for the device and open source drivers. Open source files are never as good as the closed sourced versions. It is something you accept when you use custom roms.
Click to expand...
Click to collapse
But what I wanted to say is exactly opposite I noticed much better accuracy with custom ROMs than with stock roms.
My next question was like "is there any way I can improve stock GPS accuracy" by installing "somethig" from custom ROM, but I guess it's not that simple.

Related

[Q] AOSP or true custom ROM

I've been following the development of so-called ROMs for the Vibrant (and other SGS devices), but I have yet to see a single AOSP ROM. Even when Samsung released the original kernel sources for 2.1, there were no AOSP 2.1 ROMs. Why not? Is it because they don't know which BLOBs to pull for insertion or the proper vendor overlays?
Some developers have done great work with SGS kernels (especially supercurio and his Voodoo kernels ... eugene373's tend to always wipe the internal SD card unnecessarily ...). But, a kernel does not a ROM make ... therefore I ask, what is truly missing to build an AOSP ROM. I've gone through the sources, but I don't follow makefiles too well.
I know we have another month or so before Samsung is obligated to release their 2.2 kernel sources, but that should have no impact on 2.1 AOSP ROMs. Therefore, I ask "what is the hold up?" What is missing, and what might I contribute ...
Need 2.2 source code...
2.1 is a dead horse--why bother when 2.2/2.3 are out?
The reason to bother is to at least get AOSP running. Once its on 2.1, it'll be easier to get 2.2 AOSP running on it. But claiming 2.1 is a "dead horse" is the wrong path ... the real question still stands: after 9 months on the market their still are no AOSP ROMs.
MIUI
Now that vibrant 2.2 source is released ... we finally have a REAL AOSP port and my all time favorite from my old HD2 the MIUI.... so keep your heads up and wait for it to get finished.
Get a custom rom. There are so many good devs doing them don't waste your time on AOSP....... until they release the actual source code...... on April 22
sarim.ali said:
Now that vibrant 2.2 source is released ... we finally have a REAL AOSP port and my all time favorite from my old HD2 the MIUI.... so keep your heads up and wait for it to get finished.
Click to expand...
Click to collapse
Except, the 2.2 source for the Vibrant has not been released. The SGH-T959D that shows Froyo sources on Samsung's site is for the Canadian Fascinate, not the US T-Mobile Vibrant. Samsung has yet to release the 2.2 sources.
oka1 said:
Get a custom rom. There are so many good devs doing them don't waste your time on AOSP....... until they release the actual source code...... on April 22
Click to expand...
Click to collapse
Except the so-called "custom ROMs" are just modifications on the stock theme, a replacement kernel and a change of some of the supplied applications.
There is nothing close to a full "custom ROM" such as CyanogenMod or MIUI because we don't have Samsung's sources. What is passing for a "custom ROM" for the Vibrant are just repackaged files. It is akin to the "ROM cooking" that took place for the WinMo phones, not a truly ground-up build from source that is possible with Android.
EDT/Devs4Android has the MIUI build. From Source.
TW has a 2.2.1 in testing.
EDT has a 2.2.1 Beta released.
TW has a 2.3 AOSP in testing. From Source.
EDT has 2.2 AOSP in testing. From Source.
What you want is out there for you.
Watch the forums and reply when a call for Alpha testers is posted.
Hopefully it won't be long before you see a full TW/EDT/Devs4Android collaboration!
I think what the original poster is trying to ask (and I have the same question) is why were there never any real 2.1 AOSP, cyanogen5 for the vibrant. The source for 2.1 has been around for many months. Were some other proprietary bits missing, was the released source code such a mess that it was unbuildable, something else? With those questions in mind, why will things be any different when the 2.2 source comes out?
mattb3 said:
I think what the original poster is trying to ask (and I have the same question) is why were there never any real 2.1 AOSP, cyanogen5 for the vibrant. The source for 2.1 has been around for many months. Were some other proprietary bits missing, was the released source code such a mess that it was unbuildable, something else? With those questions in mind, why will things be any different when the 2.2 source comes out?
Click to expand...
Click to collapse
Yes, this is more towards what I was getting at. We do not have Samsung's kernel sources for 2.2. And, we do not have a Samsung provided vendor overlay.
When we receive these two pieces, then a true AOSP build will be possible. However, we do have the 2.1 kernel sources, so why wasn't a true AOSP build possible then? What was missing, and can we actually expect Samsung to release the overlay that's needed?
Actually, that's true. I know it was old but why didn't anyone build a 2.1 cyanogen or aosp rom? (Not to say its easy.)
Sent from my SGH-T959 using XDA App
A noob question, kindly can someone explain what is the vendor overlay stuff?
Many thanks!
Where have you been?
rpcameron said:
I've been following the development of so-called ROMs for the Vibrant (and other SGS devices), but I have yet to see a single AOSP ROM. Even when Samsung released the original kernel sources for 2.1, there were no AOSP 2.1 ROMs. Why not? Is it because they don't know which BLOBs to pull for insertion or the proper vendor overlays?
Some developers have done great work with SGS kernels (especially supercurio and his Voodoo kernels ... eugene373's tend to always wipe the internal SD card unnecessarily ...). But, a kernel does not a ROM make ... therefore I ask, what is truly missing to build an AOSP ROM. I've gone through the sources, but I don't follow makefiles too well.
I know we have another month or so before Samsung is obligated to release their 2.2 kernel sources, but that should have no impact on 2.1 AOSP ROMs. Therefore, I ask "what is the hold up?" What is missing, and what might I contribute ...
Click to expand...
Click to collapse
Dude theres been a true AOSP ROM for the Vibrant since like december and thats CM 6.1
Im running it now
rpcameron said:
I've been following the development of so-called ROMs for the Vibrant (and other SGS devices), but I have yet to see a single AOSP ROM. Even when Samsung released the original kernel sources for 2.1, there were no AOSP 2.1 ROMs. Why not? Is it because they don't know which BLOBs to pull for insertion or the proper vendor overlays?
Some developers have done great work with SGS kernels (especially supercurio and his Voodoo kernels ... eugene373's tend to always wipe the internal SD card unnecessarily ...). But, a kernel does not a ROM make ... therefore I ask, what is truly missing to build an AOSP ROM. I've gone through the sources, but I don't follow makefiles too well.
I know we have another month or so before Samsung is obligated to release their 2.2 kernel sources, but that should have no impact on 2.1 AOSP ROMs. Therefore, I ask "what is the hold up?" What is missing, and what might I contribute ...
Click to expand...
Click to collapse
For probably the same reason that many phones with non AOSP firmware running 1.5/1.6 did not bother with AOSP 1.5/1.6 when they were released around the time 2.1 source hit. Why bother developing at all for what is essentially an "out of date" OS.
The only people it seems who actively continue to develop for existing (as opposed to new) firmware are manufacturers and carriers. This stupidity should be left to the manufacturers who still do this.
One of the larger snags way back then (sits in his rocking chair on the porch) was a lack of understanding of the phones proprietary aspects and how to work around them. But we have a fairly clear understanding of Samsung's boot process now, and RFS can now easily be turned into a distant memory.
I would wager a guess that the apathy towards 2.1 will not repeat itself once we have 2.2 source widely available and the low level similarities between 2.2 and 2.3 should have Gingerbread being more than the experiment it currently is. It's been barely more than a week since Eugene's little present manifested and there are already proper and stable kernels available.
Keep in mind that the devs we do have, have done a phenomenal job of cleaning up, speeding up, and drastically enhancing our existing 2.2 release. And perhaps to the point where many will not really care, though I know many would still like to see CyanogenMod6/7 properly on this phone.
Master&Slaveā„¢ said:
Dude theres been a true AOSP ROM for the Vibrant since like december and thats CM 6.1
Im running it now
Click to expand...
Click to collapse
Um, that's not quite true. The CyanogenMod.com website lists 0 files available for download for either experimental or stable files. The CM6.1 you must be running is not a true CM build.
Also, CM is not AOSP, but rather AOSP with modifications.
phrozenflame said:
A noob question, kindly can someone explain what is the vendor overlay stuff?
Many thanks!
Click to expand...
Click to collapse
The vendor overlay tells the AOSP build system which proprietary files are needed from the device that are not available in source form. This includes things like GPS and video drivers, baseband firmware for wireless radios, &c.
hi everybody !
a month age i decided to compile a new rom for my Galaxy S absolutely from AOSP source ( branch 2.2.1_r1 ) after some compile-time problem and many painful steps to resolve ,eventually the rom successfully built and can boot it up flawlessly on emulator.
i create a nandroid backup of current rom and installed the compiled one. but i am facing new problem :
1- the phone successfully boots but after short while screen began
flicking several time and the phone go in deep sleep and never wakeup
( power button or menu button does not do any thing )
2- touch screen works only for some second that I can unlock the
phone
3- there is no network available
4- I have downloaded samsung opesource package for GT-I9000. it
contains a folder named 'platform' but when i merge these files to
AOSP , the compile process stops and fails again. if there any one can
help me which files from samsung source should i merge and how ? if
you now the answer and dont have spare time then some internet link or
online document is really useful .i have no problem studding and
reading and searching . reaching to target is my only hope .
I am really disappointed why there is not a good and complete step2step tutorial to compile an AOSP rom for galaxy s (GT-I9000) !!
such docs is available for phones like dell streak , desire , dream , magic , .... . i really want to to active these aspect on XDA forum and with help of all you ( mods and masters ) try to create such tutorial that any one in world can use to refer . i think XDA is the only reference on net to collect and create such help and document. please help me and leave PM or comment to agree ot disagree and from where can i start ?!! thank in advanced .
edit :
there is a google groups post that i send my question in Android-platform . if you prefer please join this group and active that post to ask any question related to 'galaxy s compile from source ' .
post located at http://groups.google.com/group/android-platform/browse_thread/thread/da5d6f18f3bd3c9b

Making Flashing and Updating our device's a little more easy.

This is a call out to all existing and future developers of Xperia MDPI Devices.
For about a month now there is an app called Update Me Smartphone, which basically gives OTA update functionality for our Custom Roms.
From 01/05/2012 the developer of this app has given it a very interesting feature. You can view all Roms compatible with the Update Me Smartphone application. Even though you get a list a bunch of irrelevant devices, I suppose if we all "help" him with our suggestions he can make an application that will be on par with the Rom Manager app for devices that are fully supported by CWM.
To make this as simple as possible....
User "A" wants to download a new Rom for his Xperia MDPI Device. He has already downloaded and flashed a custom kernel (whether this is a Stock Kernel, or a CM kernel), then proceeds to download the app, install it and browse any compatible Rom's with his device... From then on his device will stay updated, through the Update Me application providing OTA updates of the Rom he has installed. If he wished to download another rom (compatible with the kernel he has - there are 3 Different Kernels AFAIK: GB CM, ICS CM, GB-ICS Stock Sony Kernel) he will just proceed to download the latest version of the rom he has selected straight to his device. No need to download to your computer, then connect the device, then copy it, then flash it. If you have the compatible kernel already installed, then its easy as pie.
Please let me know of your thoughts on this...
Edit: Link to the application's thread http://forum.xda-developers.com/showthread.php?t=1590170
Edit 2: Apart from Rom's we can also implement various mods, tweaks, fixes, etc for our devices. Even though that would be extremely hard, due to the fact that all these files need to be stored in a direct download location like Dropbox, its is a viable option.
OMG I love the idea, that would be awesome!!
It's very interesting, thanks a lot for the info I will try it!
Some modification: In GB we have 3 different kernel (Stock Based, CM Based, MIUI Based [not released yet]). In ICS we don't have Stock based to Xperia MDPI, because Sony don't released yet the stock for us. So we have CM9 based, AOSP based (it's work with CM9 ROMs btw), and ported Stock based.
Some another notice: I saw a lot of thread (not only in this forum), but sooo many people trying to make ROMs. It's not a problem, but some guy don't know some full minimum things... So who will help this guys to add this app to their ROMs?
Are you using a different Kernel for the Sony ICS rom port? I mean the Ramdisk is the same size and you're using the same zImage from a stock GB rom correct?
Well nobody is forced to do this. All we have to do is provide the app developer a link with the update_me_check.xml so that he will sort of add a link for that in the application.
By the way, i now got my goo.im account, and this have own OTA app. I will try it, and I will report.
But I know, this is not only OTA app... Hmm... I need to think in it
So the only developer checking the thread is Expeacer?
Ok...
dumraden said:
So the only developer checking the thread is Expeacer?
Ok...
Click to expand...
Click to collapse
What makes you think like this?
Well, it's been a couple of days since I posted this, either people dont have an opinion of their own, or they don't care...
dumraden said:
Well, it's been a couple of days since I posted this, either people dont have an opinion of their own, or they don't care...
Click to expand...
Click to collapse
I also read quite a lot of topics, but I don't respond in every topic.

[Q] Kernels and Android Versions

I'm not understanding how kernels and ROMs connect. Can someone give me some extra insight?
[Hardware] <-- Unique to every phone
--
[Kernel] <--- Tells the OS how to talk to the hardware
--
[ROM] <--- Slightly confused. Is the OS in the Read only Memory, or has this term changed its "street" meaning?
I understand that most ROMs (e.g. CM7 and CM9) include both the kernel and the ROM, but can you flash these separately too?
I have a 1.5 year old thunderbolt that's rooted, and has CM7 which is based on gingerbread. I believe HTC has also released the kernel as open source, which is probably the reason I have CM7
Anyway, I guess what I'm looking for is an answer/guide/forum that explains why I can't install newer versions of android onto the already working/open source kernel I'm already running. Is it accurate to view the kernel as all the phone's drivers, or just the CPU driver? If that statement is true, why can't I load ICS or Jelly Bean onto my already existing set of drivers?
I'm thinking about starting a Wiki on this if 1) it doesn't already exist, and 2) I can wrap my brain around it enough to share with others!
Thanks to anyone with a response!
shadowrelic said:
I'm not understanding how kernels and ROMs connect. Can someone give me some extra insight?
[Hardware] <-- Unique to every phone
--
[Kernel] <--- Tells the OS how to talk to the hardware
--
[ROM] <--- Slightly confused. Is the OS in the Read only Memory, or has this term changed its "street" meaning?
I understand that most ROMs (e.g. CM7 and CM9) include both the kernel and the ROM, but can you flash these separately too?
I have a 1.5 year old thunderbolt that's rooted, and has CM7 which is based on gingerbread. I believe HTC has also released the kernel as open source, which is probably the reason I have CM7
Anyway, I guess what I'm looking for is an answer/guide/forum that explains why I can't install newer versions of android onto the already working/open source kernel I'm already running. Is it accurate to view the kernel as all the phone's drivers, or just the CPU driver? If that statement is true, why can't I load ICS or Jelly Bean onto my already existing set of drivers?
I'm thinking about starting a Wiki on this if 1) it doesn't already exist, and 2) I can wrap my brain around it enough to share with others!
Thanks to anyone with a response!
Click to expand...
Click to collapse
You are correct about the ROM, but ROMs also include the kernel (if it didn't, or no kernel was flashed separately, the device would not boot). Yes, other kernels can be flashed on your existing ROM, but it's not necessarily going to be compatible.
Sort of, but there's a lot more than that. See here and here. Later versions of Android will require newer drivers,etc. which the existing kernel won't provide (they'll be outdated). Back porting and additional coding is theoretically possible, but insanely difficult (many times). Even after this some things may still not work.
Thanks for the insight, I was able to get a lot deeper into this with those links. For anyone else wandering down a similar path, you might as well stop now! Here are a few links:
http://forum.xda-developers.com/showthread.php?t=1039217&page=2#17
http://www.cs.uwc.ac.za/~mmotlhabi/avmk.pdf
http://www.iteachandroid.com/2012/01/what-is-firmware-rom-and-firmware.html
So, if anyone else is still listening, I do have two more questions:
Do any phones have truly open source drivers? (a.k.a. higher probability of allowing old hardware to work with new android OS)
Is there any way to determine which phones will be supported by the custom-ROM community early on? I know the Nexus line doesn't have vendor modified code, is that the direction which would have the highest probability to stay at top of the Custom ROM curve without upgrading devices every year?
Thanks again for any insight! I hope I'm posting this in a Newb-Friendly forum!
shadowrelic said:
Thanks for the insight, I was able to get a lot deeper into this with those links. For anyone else wandering down a similar path, you might as well stop now! Here are a few links:
http://forum.xda-developers.com/showthread.php?t=1039217&page=2#17
http://www.cs.uwc.ac.za/~mmotlhabi/avmk.pdf
http://www.iteachandroid.com/2012/01/what-is-firmware-rom-and-firmware.html
So, if anyone else is still listening, I do have two more questions:
Do any phones have truly open source drivers? (a.k.a. higher probability of allowing old hardware to work with new android OS)
Is there any way to determine which phones will be supported by the custom-ROM community early on? I know the Nexus line doesn't have vendor modified code, is that the direction which would have the highest probability to stay at top of the Custom ROM curve without upgrading devices every year?
Thanks again for any insight! I hope I'm posting this in a Newb-Friendly forum!
Click to expand...
Click to collapse
For both your questions, the Nexus-line devices would be the way to go. They usually have everything working on new Android versions the soonest, and Google always releases their code, etc.
Hi
i can use linux kernel (zimage) to update android kernel if yes ,how ?
thnx

[Q] Kernels - what is there to know about them ?

OK, so here's the thing... I'm kind of new in the Android acknowledgement, so I hope that here will be the place where I will get my answers. So here's what I know...
At first I didn't know that Android was Java-based, using a modified Linux kernel which we all know it's C-based (entirely). After a while, I found that there were different firmwares (ROMs) from the original ones, called Stock ones and also different kernels. After reading lots of info about how things actually are, I've decided to root my stock and then I moved to a custom MIUI for my SGSII with a JB implementation. At first it was great, but I had some issues which left me disappointed. Then I moved on to the official MIUI (China - English one). Things got better after I got used to it. The major bugs disappeared, only small ones left and a few crashes, but in time most of them got fixed. Later it crossed my mind, "Why are there so many different kernels and which is the best one for my phone or ROM to be precise?" Well this is where I need your help. I've read some topics that siyah kernel is probably the best kernel, which fits the MIUI rom. The pointing of concrete kernels isn't the kind of answer I was actually searching for. To be honest, I need answers to questions like:
How many kernels are there ?
Which ones are safe ? (I've read that there are badly written ones, so yeah, it needs to be asked)
Statistically, which is the best kernel and is it for the MIUI rom ?
How can I tell that it's suitable for the MIUI rom ? (Since I've read that not all are)
What are the risks of changing the kernel?
How can you test the kernel's behaviour, an app which makes statistics in time or some other methods ?
Believe me, as annoying this topic might seem, lots of us (the newbie users) are burning up the google servers, just to find these answers. I'm really hoping for a reply spam with answers (if possible , spare the trolling ones). Thanks for reading my annoying topic, anyway
Since most of the source is available, basically anyone can build their own kernel at home, so it is hard to tell how many kernels are there.
what isn`t available as open source are most of the OEM-specific drivers. Samsung, for one, doesn`t make most of the drivers' source publicly available, so kernel developers have to make a binary kernel around the binary drivers and literally pray their work well together.
Siyah is safe, but I prefer the stock kernel (I like the stock ROM... go figure). The stock kernel is the only one that is sure to work properly with all the hardware in the phone, because it is the only built from sources for the drivers as well (read my previous paragraph).
Which ones are safe (other than stock and Siyah): you gotta try them for yourself, read other users' remarks and feedbacks, and so on.
Risks:
Very low. As long as the bootloader is good, if the kernel totally malfunctions, just reboot in download mode and flash something else.
Some app may work very well in one kernel and bomb in another. It may crash in some kernels. It is very empyrical.
The problem is that custom kernels don't undergo the same type of quality testing as stock kernels. Developers have very limited resources to do that, and some developers are more interested in having a short time-to-market than a quality product (well, many large corporations act like that as well). At the end of the day we - power users - are the beta testing and quality assurance teams for the kernel developers.

Firmware from Meizu or other devices

Has anyone tried to put the firmware of devices from meizu, xiaomi? For example, CM 13?Supposed to work? Support scanner available from meizu , and the seams are already stable
It's not possible to do that. Any ROM that you load into a phone must be built for that particular model. Although non-stock ROMs are available for many phones, including the P9000, they are all built using the kernel (which is the bit of code that controls the hardware - device drivers, if you like) of the stock ROM supplied by the manufacturer. So you can tweak the original ROM and sometimes add new features (if you have the skill to do it, of course, it's not a simple task), but you can't just load up CM13, for instance, from a Meizu phone.
RMcT said:
It's not possible to do that. Any ROM that you load into a phone must be built for that particular model. Although non-stock ROMs are available for many phones, including the P9000, they are all built using the kernel (which is the bit of code that controls the hardware - device drivers, if you like) of the stock ROM supplied by the manufacturer. So you can tweak the original ROM and sometimes add new features (if you have the skill to do it, of course, it's not a simple task), but you can't just load up CM13, for instance, from a Meizu phone.
Click to expand...
Click to collapse
thank you for such a detailed explanation, very grateful???

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