Dealing with a picture frame that freezes.

I recently bought myself a (1920×1080 pixel) digital picture frame, that had rave reviews among other customers, but that began the habit of freezing after about 12 hours of continuous operation, with my JPEG Images on its SD Card.

This could signal that there is some sort of hardware error, including in the internal logic, or of the SD Card itself. And one of the steps which I took to troubleshoot this problem was, to try saving the ‘.jpg’ Files to different SD Cards, and once even, to save those pictures to a USB Key, since the picture frame in question accepts a USB Memory Stick. All these efforts resulted in the same behaviour. This brought me back to the problem, that there could be some sort of data-error, i.e., of the JPEG Files in question already being corrupted, as they were stored on my hard drives. I had known of this possibility, and so I already tried the following:

 


find . -type f -name '*.jpg' | jpeginfo -c -f - | grep -v 'OK'

 

Note: To run this command requires that the Debian package ‘jpeginfo’ be installed, which was not installed out-of-the-box on my computer.

This is the Linux way to find JPEG Files that Linux deems to be corrupted. But, aside from some trivial issues which this command found, and which I was easily able to correct, Linux deemed all the relevant JPEG Files to be clean.

And this is where my thinking became more difficult. I was not looking for a quick reimbursement for the picture frame, and continued to operate on the assumption that mine was working as well, as the frames that other users had given such good reviews for. And so, another type of problem came to my attention, which I had run in to previously, in a way that I could be sure of. Sometimes Linux will find media files to be ‘OK’, that non-Linux software (or embedded firmware) deems to be unacceptable. And with my collection of 253 photos, all it would take is one such photo, which, as soon as the frame selected it to be viewed, could still have caused the frame to crash.

(Updated 1/16/2020, 17h15 … )

Continue reading Dealing with a picture frame that freezes.

Continuing to Troubleshoot my Graphics Chip

The computer named ‘Phoenix’ has now been running for 6 days and 19 hours. It is approaching the point, where recently it used to crash. I have suspected that my graphics chip might be the problem, and that more specifically, this might have happened, because the graphics chip is only supposed to take 128MB of shared RAM according to the BIOS, but according to which it has been allocated 256MB, by the Linux software. It is an outdated graphics chip, which I have written about here.

Under Linux we have numerous tools that give us information about our machines, including the ‘‘ here:

phoenix_ram_2

I have already written that I cannot take the 70MB of shared RAM as an exact figure, of how much VRAM the chip is taking, which is actually system memory in this case, because there could be other processes using shared memory in some way. Yet, this is still an approximate estimate, and, since the amount being indicated is 70MB, the total amount of shared memory taken by my graphics chip, cannot be greater than 71MB.

This basically rules out one hypothesis for what might have been happening. Under normal use, the chip will not need more than 128MB.

Now, the fact that I have installed a new case fan, may or may not protect me from future crashes, since my other main hypothesis was, ‘Something could have been overheating on the motherboard.’

(Edit 02/14/2017 : )

And this is what my shared memory looked like today, 8 days and 23 hours after the latest reboot:

phoenix_ram_3

( 59+ MB – Stable )

Dirk

 

I question the amount of VRAM on Phoenix.

I am still contemplating, why the server-box I name ‘‘ was crashing, and my attention keeps coming back to the graphics chip. Before this computer was resurrected, it was running in 32-bit mode, as ‘‘. At that time, it only had 2GB of RAM. But now it runs in 64-bit mode, with 4GB of RAM.

When I boot, the BIOS message still tells me that it has 128MB of shared memory, for the graphics chip. But strangely enough, the piece of text I pasted into this posting, reads that the graphics driver has set aside 256MB of VRAM, near the top of the 4GB of physical addresses. I did not know that the kernel can override a BIOS setting in this way, let us say just because processing has been switched to 64-bit mode.

One mishap which could naively go wrong, is that the legacy driver, unaware of the specifics of this motherboard, could be allocating 256MB of shared memory, but that physically, the hardware cannot share past the address ‘‘. That is, the address ‘‘ may have become forbidden territory for the graphics card. It is however uncommon, that the programmers of kernel-space modules, would make such a simple mistake.

This is a 64-bit system, which only accepts up to 4GB of RAM, thus only possessing 32-bit physical addresses, to go with its 64-bit virtual addresses.

According to this screen-shot:

phoenix_ram_1

I only have 3.74GB of RAM available to the system, instead of 4GB. The reason for this, is the fact that 256MB have in fact been reserved for the graphics chip. By itself this would seem to suggest, that the allocation has succeeded.

Also, the fact that 49.26MB of shared memory was momentarily being indicated, is not too telling, because several types of processes could be using shared memory for some purpose. This feature does not only exist, for user-space processes to make texture images available to the graphics card.

Continue reading I question the amount of VRAM on Phoenix.

NoMachine NX

When people connect to their VPN, this could simply allow them to access shared files. But alternatively, this could also mean that they wish to create a virtual session, on the remote desktop of one of their servers. The latter exists under the terms VNC, RDP, XRDP, and several others.

On my main Linux server named ‘Phoenix’, I have the XRDP service installed, which is the Linux equivalent of RDP. But one main drawback of this method, of remotely accessing a desktop, is the fact that XRDP does not allow file-sharing, specifically in the version of this protocol that runs out-of-the-box from the package manager. I have read that certain custom-compiled versions support this, but do recall that this service is a mess to custom-compile, and to set up in such a way that it runs reliably. So I stick to the packaged version for now, and do not obtain file-sharing.

There exists a closed-source application named , which we could use to bridge this gap. But while their paid software subscriptions are very expensive (from my perspective), their Free software version has some big disadvantages.

First of all, even their Free version can be run in client or in server mode. I think that this is terrific. But in server mode – which affords access to the local machine desktop from elsewhere – there is no built-in support for SSH protocol. There is only the unencrypted NX protocol, for which their service listens.

Secondly, not every computer is strong enough to run in server mode. On the computer ‘Phoenix’ I have a fragile X-server, and this service has actually crashed my X-server. Not only that, but allowing this service to run on reboot, consistently prevents my X-server from starting. It gets its hooks into the session so early on boot, that the X-server crashes, before the user is even asked for a graphical log-in.

On the plus side, there are ways of solving both problems.

Continue reading NoMachine NX