CDMA devices in AOSP: technical details
Jean-Baptiste Queru
Nexus S 4G (Sprint), Motorola Xoom (Verizon Wireless), and Galaxy
Nexus (Verizon Wireless). A high-level view is
provided here: https://groups.google.com/group/android-contrib/browse_thread/thread/a61cf74b965dbde5
Here is a look at the practical technical differences between GSM and
CDMA, as relevant to these devices.
In order to properly support a given device in AOSP, the relevant
proprietary binaries need to be available. For Nexus devices, we make
as many of these as possible available through
https://code.google.com/android/nexus/drivers.html, which requires an
appropriate license agreement between Google and the owners of those
binaries. For GSM (and HSPA) devices, getting these license agreements
is relatively easy; however, since there are many more intellectual
property holders in the CDMA world, it is much more difficult to get
the appropriate rights.
On a technical level, in the GSM world the proprietary binaries that
are necessary to communicate with the cell network are typically a
very small number of C libraries that can be used directly on all
build configurations without any modifications. In the CDMA world,
parts of the network stack are implemented as apks, which are
protected by cryptographic signatures, and the network stack must use
the same signature as the rest of the system (to guarantee that it
can't be replaced in a way that'd allow the network traffic to be
intercepted). Since the system signature varies from one build
configuration to the next, those apks need to be modified to match
each build. In turn, that requires licenses that allow making
modifications to those files, and Google hasn't been able to obtain
such a license so far. Similarly, the build process for consumer
builds involves a step called "dexpreopt" that modifies all the apks
on the system, and running that step also requires licenses that allow
making modifications to the proprietary binaries, so doing it on a
CDMA device requires additional licence terms that aren't necessary
for GSM devices.
Even if the licensing issues were resolved, there'd still be some
hurdles that'd prevent CDMA devices from working as well as GSM ones
in AOSP. As an example, performing a factory reset on Xoom (which is
necessary to work around a bootloader bug) deletes the network
configuration for Verizon Wireless, and that network configuration
can't be restored in AOSP builds as it is tied to the initial sign-up
flow, which isn't the same for AOSP builds and retail builds.
Now, here's how things are likely to look in the future for those CDMA devices:
- Most likely, the relevant source files will continue being in the
Android source tree.
- Quite likely, it will be possible to actually compile that code.
- We plan to continue to distribute factory images for Galaxy Nexus
and proprietary binaries for all relevant devices, where we can.
- There won't be any testing done on AOSP builds for those CDMA
devices, so they'll probably bit-rot.
- CDMA devices won't be targeted by improvements in the way AOSP
builds can be installed or distributed.
JBQ
--
Jean-Baptiste M. "JBQ" Queru
Software Engineer, Android Open-Source Project, Google.
Questions sent directly to me that have no reason for being private
will likely get ignored or forwarded to a public forum with no further
warning.
Borgey
way. We've been pretty much fooled into thinking this phone would have
AOSP support at the time of purchase only to get it taken away 2
months after? Just because Google can't make a deal with people who
own licenses should NOT be consumers problem since we've already came
through on our part of the deal (paying for the phone). Now Google
needs to remain TRUE to their word and give us what we were promised
when we purchased a Nexus device.
On Feb 6, 4:22 pm, Jean-Baptiste Queru <j...@android.com> wrote:
> You may have heard about a change in AOSP support for 3 CDMA devices:
> Nexus S 4G (Sprint), Motorola Xoom (Verizon Wireless), and Galaxy
> Nexus (Verizon Wireless). A high-level view is
> Here is a look at the practical technical differences between GSM and
> CDMA, as relevant to these devices.
>
> In order to properly support a given device in AOSP, the relevant
> proprietary binaries need to be available. For Nexus devices, we make
Jean-Baptiste Queru
We really intended to get better support for CDMA devices, on par with
GSM devices. That was definitely the original plan, but sometimes even
the best plans bump into difficulties. With appropriate licenses and a
bit of help from the manufacturers and operators to tie the loose
ends, there's no fundamental technical reason why that shouldn't be
possible.
Unfortunately no matter how much I might desire to distribute the
missing proprietary binaries in a form that's appropriate for use with
AOSP, I can't possibly do that without appropriate licenses. Without
those files, there's no way to honestly claim that AOSP is supported
on those devices.
JBQ
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Borgey
just got cheat out of a Nexus........ big time
Ievgenii Nazaruk
For example an external .zip archive with all the META-INF folder
content:
some-app.apk
some-app.sig <- external signature, exact copy of META-INF folder
This external signature should have priority over the internal one for
this
mechanism to work. Some modifications should be done to the
package manager of course. But that's not impossible.
On Feb 6, 11:22 pm, Jean-Baptiste Queru <j...@android.com> wrote:
> You may have heard about a change in AOSP support for 3 CDMA devices:
> Nexus S 4G (Sprint), Motorola Xoom (Verizon Wireless), and Galaxy
> Nexus (Verizon Wireless). A high-level view is
> Here is a look at the practical technical differences between GSM and
> CDMA, as relevant to these devices.
>
> In order to properly support a given device in AOSP, the relevant
> proprietary binaries need to be available. For Nexus devices, we make
Jean-Baptiste Queru
-It requires to modify an extremely sensitive part of the package
manager, for a use case that's not relevant for retail devices, so the
risk-reward balance is heavily stacked against AOSP. At the very least
you'll want that behavior to be off by default, with a mechanism to
turn it on that would only be enabled in custom AOSP builds.
-It requires to generate those signatures without copying the files,
i.e. they'd need to be generated on-device, with a usage pattern that
isn't the normal usage pattern for those files.
I agree that with those two aspects we'd be potentially one step
closer toward being able to do http://goo.gl/8jit8 on some CDMA
devices.
JBQ
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Brad Gogats
Prem Kumar
drivers but can benefit from all the other drivers such as Wifi etc?
We recently got several CDMA phones and it is a shame to have to
switch to GSM without much notice.
On Feb 6, 3:34 pm, Jean-Baptiste Queru <j...@android.com> wrote:
> It's theoretically possible, but bumps into two aspects:
>
> -It requires to modify an extremely sensitive part of the package
> manager, for a use case that's not relevant for retail devices, so the
> risk-reward balance is heavily stacked against AOSP. At the very least
> you'll want that behavior to be off by default, with a mechanism to
> turn it on that would only be enabled in custom AOSP builds.
>
> -It requires to generate those signatures without copying the files,
> i.e. they'd need to be generated on-device, with a usage pattern that
> isn't the normal usage pattern for those files.
>
> I agree that with those two aspects we'd be potentially one step
Ezekeel
distributing them would break copyright law, what about pulling the
proprietary binaries from the device during the installation process,
resigning them on-the-fly with keys fitting for that custom ROM and
putting them back? I guess that would break the EULA the user has
agreed to, but do I see it right that this would not break the
copyright? Would this be a way for the Android community to legally
distribute custom ROMs for CDMA devices?
On Feb 6, 10:22 pm, Jean-Baptiste Queru <j...@android.com> wrote:
> You may have heard about a change in AOSP support for 3 CDMA devices:
> Nexus S 4G (Sprint), Motorola Xoom (Verizon Wireless), and Galaxy
> Nexus (Verizon Wireless). A high-level view is
> Here is a look at the practical technical differences between GSM and
> CDMA, as relevant to these devices.
>
> In order to properly support a given device in AOSP, the relevant
> proprietary binaries need to be available. For Nexus devices, we make
Pete
around $600 (either directly or through contract) for what was being
sold as "the premier google developer phone".
If I bought a car with 4 tires, and 3 weeks later the seller showed up
to remove 1 of them, there would be a lawsuit.
Google didn't just figure this problem out, coinciding with the first
wave of everyone purchasing the Nexus. I have no doubt, at this point,
that the difficulties had a role in the delay of the release, but
someone figured that "we got a lot of phone to unload, let's get them
purchased before they find out"... I'm certain that some
entrepreneurial law team will figure out a way to get to the bottom of
this.
Jean-Baptiste Queru
modify files without a license? This is a legal question, but since
I'm definitely not a lawyer, absolutely not a DMCA lawyer, and
undoubtedly not your lawyer, there is definitely absolutely
undoubtedly no way I can answer that question.
I suggest that you look at the details of http://goo.gl/8jit8 to see a
case where I take great care about not copying or modifying such
files. I also created the very annoying packaging of Samsung's
binaries for crespo4g binaries so that the exact files that get
distributed in the self-extractor remain unmodified.
JBQ
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Skynet11
toro? Would this allow developers to legally build custom AOSP ROMs
for CDMA?
On Feb 7, 10:57 am, Jean-Baptiste Queru <j...@android.com> wrote:
> Putting together instructions and/or tools for people to copy and
> modify files without a license? This is a legal question, but since
> I'm definitely not a lawyer, absolutely not a DMCA lawyer, and
> undoubtedly not your lawyer, there is definitely absolutely
> undoubtedly no way I can answer that question.
>
Jean-Baptiste Queru
with a few of them.
Also, again, I'm not a lawyer, and i'm not your lawyer, so I can't
possibly answer questions about whether something is legal or not.
The approach I took for the GSM Galaxy Nexus (installing via recovery,
leaving proprietary files entirely untouched in the process)
definitely doesn't for for the CDMA version, because the proprietary
files on that device need to be modified in order to work with a
custom build, and the tools I used don't allow doing anything like
that.
JBQ
> For more options, visit this group at http://groups.google.com/group/android-platform?hl=en.
Skynet11
benefit from: Is it conceivable that AOSP does automatically re-sign
the proprietaries during compile time?
On Feb 7, 2:13 pm, Jean-Baptiste Queru <j...@android.com> wrote:
> Well, I can't speak about all CDMA devices, since I'm only familiar
> with a few of them.
>
> Also, again, I'm not a lawyer, and i'm not your lawyer, so I can't
> possibly answer questions about whether something is legal or not.
>
> The approach I took for the GSM Galaxy Nexus (installing via recovery,
> leaving proprietary files entirely untouched in the process)
> definitely doesn't for for the CDMA version, because the proprietary
> files on that device need to be modified in order to work with a
> custom build, and the tools I used don't allow doing anything like
> that.
>
> JBQ
>
>
>
>
>
>
>
>
>
> On Tue, Feb 7, 2012 at 11:04 AM, Skynet11 <jmcintir...@gmail.com> wrote:
> > Would this approach be possible for other CDMA devices, including
> > toro? Would this allow developers to legally build custom AOSP ROMs
> > for CDMA?
>
> > On Feb 7, 10:57 am, Jean-Baptiste Queru <j...@android.com> wrote:
> >> Putting together instructions and/or tools for people to copy and
> >> modify files without a license? This is a legal question, but since
> >> I'm definitely not a lawyer, absolutely not a DMCA lawyer, and
> >> undoubtedly not your lawyer, there is definitely absolutely
> >> undoubtedly no way I can answer that question.
>
Jean-Baptiste Queru
which can't be done without a license.
-That'd require to modify the proprietary files, which can't be done
without a license.
JBQ
> For more options, visit this group at http://groups.google.com/group/android-platform?hl=en.
Nathaniel Husted
the Android division at Google would use its bully pulpit and pressure
companies to provide more "open" alternatives in this regard. Google
is in a particularly unique position given an OS stack that is already
open source thus providing a great basis for an open mobile platform.
I commend the progress of the AOSP team (which I assume to be a...
very... small subset of the Android building as a whole) to open up
Android as much as it can, it sometimes feels as though for every two
steps that are made, the carriers' stubbornness puts us three steps
back. It appears as if they unable to release their anachronistic
viewpoint on wireless data networks.
Cheers,
Nathaniel
Jean-Baptiste Queru
You're definitely right that there are steps forward and steps back.
Over some short periods of time, at times things move backward a bit,
often as a result of trying to move too far forward and then having to
retreat a bit.
I do believe however that things have been moving forward overall. As
high-level examples, we now have unlockable bootloaders in retail
devices (starting with Nexus One). We now have licenses for some of
the proprietary binaries (starting with Nexus S). We now have official
factory images (starting with Galaxy Nexus).
JBQ
S 'Dis' McCarthy
(http://gotgame.com/2011/12/13/linux-lawsuityou-have-been-dismissed/)
Jean-Baptiste Queru
Apks on retail images are run through dexopt at build time, replacing
the dex section with an odex file. The resulting odex files are
optimized globally along library dependencies. An apk that's been run
through dexopt can only run against the exact libraries that were used
in the same dexopt phase.
What that really means is that even if we managed to get the package
manager to recognize those apks as having the platform signature (one
way or another), we still wouldn't be able to execute the code in
question, as that code is only executable in the context of the system
it was original built as a part of.
That's exactly the kind of difficulty that we keep bumping into when
we don't have the appropriate licenses, especially for apks.
JBQ
Ashwin Gururaghavendran
purchased for developing custom ROMs and other system modifications
that I can redistribute. But now it looks like it would be tough for
even myself to build and get such a fully working custom ROM.
The amount we pay for these devloper devices is substantial - and I'm
sure Google would have had this foresight/information about such
problems way ahead. The appropriate thing from Google's side for us
developers would have to give few warnings about such grey areas (at
least for the Verizon Galaxy Nexus) before the phone was available for
sale on the retail market.
Jean-Baptiste Queru
JBQ
adam darst
google was blind sided by something you claim to be so.obvious??? Are
you that ignorant as a major player?
On Feb 6, 4:22 pm, Jean-Baptiste Queru <j...@android.com> wrote:
> You may have heard about a change in AOSP support for 3 CDMA devices:
> Nexus S 4G (Sprint), Motorola Xoom (Verizon Wireless), and Galaxy
> Nexus (Verizon Wireless). A high-level view is
> Here is a look at the practical technical differences between GSM and
> CDMA, as relevant to these devices.
>
> In order to properly support a given device in AOSP, the relevant
> proprietary binaries need to be available. For Nexus devices, we make
Jean-Baptiste Queru
JBQ
> You received this message because you are subscribed to the Google Groups "android-platform" group.
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>
>
Skynet11
and what Google should have done, because that's been covered already.
Therefore, I will simply ask: Is there any possibility that sometime
in the future Google might be able to secure the licenses it needs to
support CDMA devices in AOSP? It seems to me that Google should do
whatever it takes to honor its word that the Galaxy Nexus toro would
be a developer phone. It sounds like some of these IP owners are
putting the screws to Google and we're the ones who are caught in the
crossfire. Is this a correct assessment? Is there any hope that this
issue might eventually be resolved? Thanks in advance...
Jesse Godsey
I really do not see this happening you guys. Everything I am reading is telling me it is already a done deal. Google does not and will not any longer support CDMA devices directly. And even firmware updates only if the carriers proprietary radio files, etc. will work with Google's updated source.
The writing is on the wall, Google is no longer directly supporting cdma for Aosp building as well as not providing CDMA devices Ota updates, that will come now directly from Verizon. Verizon will nor carry another Nexus ever is my prediction. Game over.
Is there any possibility that Google might be able to secure the
licenses it needs to support CDMA devices in AOSP? It seems to me that
Google should do whatever it takes to honor its word that the Galaxy
Nexus toro would be a developer phone. It sounds like some of these IP
owners are putting the screws to Google and we're the ones who are
caught in the crossfire.
Skynet11
just now coming up?
Jesse Godsey
I do not know man. I think it is political
So what happened between Gingerbread and ICS so that this issue is
just now coming up?
gnarlyc
end users will make a difference? Probably not, but I'll be glad to
scream a little.
On Feb 8, 10:48 am, Jesse Godsey <jessegod...@gmail.com> wrote:
> I do not know man. I think it is political