## My Pixel C Tablet Ran Out Of Power Last Night.

I own a Google Pixel C tablet, that runs Android 8.1.0 . As is customary for me, I leave it In Standby each night, which means that it’s still drawing some small amount of current from its battery.

Usually, I’d inspect the tablet before going to bed each night, to verify that it will still have enough juice in its battery, to sleep through the night. But somehow, last night, I just failed to verify this, and assumed that the tablet was okay to sleep through the night.

Also, I slept-in this morning. Well as I was sleeping in, the tablet made a few notification sounds which I’d never heard from it before, and the fact that it was doing so did not alarm me in my sleep.

So this morning, when I tried to reboot the tablet, it would proceed partially into the boot process, and then just play its notification sound, and shut off again. So what I needed to do was leave it plugged in for two hours, and then try rebooting it again. Which worked!

But there was just a possible scenario in my mind, of what could have gone wrong last night, and what could potentially have bricked the tablet.

## Pixel C Crash Yesterday Night

Yesterday evening, my new Pixel C Tablet did something for the first time, which was ominous. Its screen just went dark, and then started to display the logo, which it displays during a restart. It followed through with a successful restart.

Some people mistakenly think that this behavior is a reboot. If we were to call it that, then this behavior would need to be called a Hard Boot – as opposed to a Soft Boot, which happens when the user shuts the tablet down from the software-side, in telling it to reboot. In fact, a Hard Boot would be happening when the user uses the power-button to force a Hard Boot, and would have an explanation in that.

In reality, what the tablet did was a spontaneous reset. This type of event is also a File System Event, as the File System was never unmounted. Hence, the tablet also needed to repair its file system when it booted anew.

But, there are certain safety-factors built into how any serious O/S works, and built into how any file system works. So in most cases, the repair to the file system succeeds.

The fact that this has happened to a brand-new tablet, causes me to question how (un)stable it might really be. I’ve only had this tablet for a few short months now.

One of the features of how this happens, which is even less reassuring, is that after the reset, there is nothing displayed in the user interface, which betrays the fact that the reset happened. What this means is that in theory, this could be happening every night as I sleep, even while the tablet is charging, because by the next morning, there would be nothing displayed, to betray the fact that it has happened.

It just happens to have taken place once now, while I was sitting in front of it.

Dirk

(Edit : )

I should add, that this tablet is running the May 5 patch of Android 7.1.2 .

## New Case-Fan Installed

During previous postings, I had written about crashes, which the computer I name ‘Phoenix’ was suffering from. And I had written that one possible reason could have been the failed case-fan, which could have been causing something on the motherboard to overheat.

Just today, this box suffered from another similar crash. This time, I opened up the case, and replaced the 92mm case-fan. Therefore, the reader might expect some optimism on my part, that this server-box will not crash again. But in reality I have two reasons, for which my optimism does not overwhelm:

1. If an overheated chip has already caused crashes, there is some tendency for it to suffer from a memory-effect, of wanting to fail again, whenever it gets slightly warm, or just so. Therefore, due to the first crash possibly having happened for that reason, this machine could now have a penchant for crashing, even though the initial cause has been removed.
2. The cause may not have been an overheated chip, but rather, a pure software-problem with the legacy graphics driver (nVidia). On such a big display, the graphics driver may have been suffering from some sort of resource leak – aka memory leak – and during boot-up, the BIOS displays it only possesses 128MB of shared RAM! Thus, the problem could be cumulative and result from regular copying-and-pasting, with many HW-accelerated drawing surfaces and many compositing effects enabled. Once we have an unstable graphics driver – and the graphics driver has received several updates recently – having a stable one could be a luxury we cannot easily reproduce.

I was down from roughly 19h00 until 20h00, and apologize to my readers for any inconvenience.

Dirk

BTW: I have an additional reason, not really to believe, that these crashes are due to an overheated graphics chip. During the actual reboot, the graphics chip should get especially hot, and especially so, if the case-fan is not turning.

I can see that if this chip did overheat, the TDR would not be able to reboot it.

But the crashes never seem to occur, directly after the reboot. I generally seem to obtain about 6 days of smooth computing, before another crash happens.

Also, it should not be a VRAM leak, because this is a pre-GPU-type graphics chip. With the old graphics chips, that maximally had several pixel and several vertex pipelines, VRAM consumption was more or less static, while with the more-modern GPUs, some amount of VRAM-creep is at least plausible.


root@Phoenix:/home/dirk# lspci | grep vga
root@Phoenix:/home/dirk# lspci | grep VGA
00:0d.0 VGA compatible controller: NVIDIA Corporation C61 [GeForce 6150SE nForce 430] (rev a2)
root@Phoenix:/home/dirk# lspci -v -s 00:0d.0
00:0d.0 VGA compatible controller: NVIDIA Corporation C61 [GeForce 6150SE nForce 430] (rev a2) (prog-if 00 [VGA controller])
Subsystem: Hewlett-Packard Company Device 2a61
Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 21
Memory at fb000000 (32-bit, non-prefetchable) [size=16M]
Memory at e0000000 (64-bit, prefetchable) [size=256M]
Memory at fc000000 (64-bit, non-prefetchable) [size=16M]
[virtual] Expansion ROM at f4000000 [disabled] [size=128K]
Capabilities: [48] Power Management version 2
Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit+
Kernel driver in use: nvidia

root@Phoenix:/home/dirk#