Pixel 9 not able to acquire GPS (gnssd errors)

joSS

I am trying out GrapheneOS on my Pixel9 today. I tested with one of the official stable builds (2025090600) and was able to install it on the Pixel, use it, etc. However, with a simple GPS test app, I found out that I'm not able to acquire my location (even though location in my settings is already enabled).

To debug this (yes, I am interested in getting involved in the code), I tried building GrapheneOS on my own so I could have access to the source code. I confirmed that my builds can be installed, they work, and similarly cannot acquire location. When checking the system logs shortly after the phone powers up, I see errors related to GNSSD. See summary of the log at the end of my post, mainly with entries containing 'gnssd'.

But when going through the source code, I can't see where such log output related to gnssd is located. Could I get some help pinpointing where in the code I need to be looking so I can investigate this issue further please?

Summary of system log with primarily 'gnssd' entries:
type: logcat
osVersion: google/tokay/tokay:16/BP2A.250805.005/2025090800:user/release-keys
flags: dev options enabled
buffers: main,system,crash,events,kernel,radio
level: verbose

--------- beginning of events
01-01 00:00:00.084 logd 438 438 I auditd : avc=type=2000 audit(0.0:1): state=initialized audit_enabled=0 res=1
09-12 21:32:29.052 logd 438 438 I auditd : avc=type=1403 audit(0.0:2): auid=4294967295 ses=4294967295 lsm=selinux res=1
09-12 21:32:29.052 logd 438 438 I auditd : avc=type=1404 audit(0.0:3): enforcing=1 old_enforcing=0 auid=4294967295 ses=4294967295 enabled=1 old-enabled=1 lsm=selinux res=1
--------- beginning of kernel
09-12 21:32:29.569 root 0 0 I trusty : boot args 0x*** 0x*** 0x6 0x0
......
09-12 21:32:39.037 1000 1262 1346 I am_cpu : [Pid=1043,UID=1021,Base Name=gnssd,Uptime=4.478s,Stime=20ms,Utime=20ms]
......
09-12 21:34:45.018 1000 1262 1346 I am_cpu : [Pid=1043,UID=1021,Base Name=gnssd,Uptime=118.834s,Stime=220ms,Utime=390ms]
......
09-12 21:34:54.278 gps 1043 1475 E gnssd : Critical Error: crash_handling_mode: Crash Handling Mode 2
09-12 21:34:54.279 gps 1043 1475 E gnssd : Critical Error: crash_handling_mode: Crash Handling Mode 2
......
09-12 21:34:54.447 gps 1043 1486 E gnssd : Critical Error: pcie_signal_cp_crash signaling CP crash recovery
09-12 21:34:54.447 gps 1043 1487 W gnssd : Warning: lal_device_error: Reported CP crash recovery
09-12 21:34:54.447 gps 1043 1487 E gnssd : Critical Error: slim_spi_device_error pcie context is NULL
......
09-12 21:34:54.549 gps 1043 1486 E gnssd : Critical Error: pcie_signal_cp_crash signaling CP crash recovery
......
09-12 21:34:54.549 gps 1043 1487 W gnssd : Warning: lal_device_error: Reported CP crash recovery
09-12 21:34:54.549 gps 1043 1487 E gnssd : Critical Error: slim_spi_device_error pcie context is NULL
......
09-12 21:34:54.653 gps 1043 1486 E gnssd : Critical Error: pcie_signal_cp_crash signaling CP crash recovery
......
09-12 21:34:54.656 gps 1043 1487 W gnssd : Warning: lal_device_error: Reported CP crash recovery
09-12 21:34:54.656 gps 1043 1487 E gnssd : Critical Error: slim_spi_device_error pcie context is NULL
......
09-12 21:34:54.780 gps 1043 1475 E gnssd : Critical Error: crash_handling_mode: Crash Handling Mode 2
09-12 21:34:54.781 gps 1043 1475 E gnssd : Critical Error: crash_handling_mode: Crash Handling Mode 2
......
09-12 21:34:55.008 gps 1043 1472 E gnssd : Critical Error: pcie_wait_for_response error/timeout
......

de0u

joSS Does GNSS work on that device while it is running Google's OS, as tested by GPSTest? I ask because those "pcie" errors look possibly consistent with a hardware issue.

I think on Pixels the GNSS app is a binary app from the chip vendor. If so, finding the source code will be tricky!

joSS

de0u Thank you very much for the quick reply! I will need to try testing with Google's OS.

Is the source code for Pixel's GNSS simply not possible at all to find? If it is available, do you have suggestions for where I could try looking? Or is it possible to implement myself? (More details: I am a grad student, and this could be a project for my course. :) )

de0u

joSS Is the source code for Pixel's GNSS simply not possible at all to find?

Though I have not seriously looked into this, I believe the GrapheneOS project ships binaries, which they would do only if the source were unavailable.

There is lots and lots of code on GrapheneOS that is binary blobs: GPU code, Wi-Fi firmware, Bluetooth firmware; I sort of think the fingerprint reader is a blob too.

joSS Is it possible to implement myself? (More details: I am a grad student, and this could be a project for my course. :) )

Many things are possible, but I am skeptical that this thing is feasible. That said, you could look for a data sheet or an SDK...

ron

GrapheneOS is only using GPS by default. network location is off. I only got my location in my home by either going outside or turning on the additonal location services (WiFi and Bluetooth Search and using the GrapheneOS proxy and Servers).