I have a PCI driver for a FPGA card that installs and works fine.However, we have a need to clean up our system without rebooting which includes unloading this driver.
When starting again (without rebooting) the driver is re-installed. I have found that when I do this process (install/uninstall) multiple times, on the 5th unload of the driver the directory associated with the device just disappears.
lspci command can no longer find my device because of a bad link. I have to reboot to get the device directory (/sys/bus/pci/devices/00000:04:00.0) to show up again.
With some experimentation and reducing the driver down to the bare minimum I discovered that if I do not do a call to pci_enable_device(..) function in my pci_probe_method, then I am able to install/uninstall the driver multiple times without error.
Of course, I need to call this method before I can do anything with the device but I wanted to be sure it was not some other of the more complex initialization I am doing was causing the problem.
I have verified that my call to pci_disable_device() is being called in the pci_remove_method(). I should be able to enable and disable a PCI device indefinitely, right? Any help in figuring out what is happening would be appreciated.
The actual solution to this problem was to eliminate an extraneous call I had to pci_dev_put(..). I did not notice this before when submitting the question. This was leftover from when this driver was not using the pci_probe() method to discover this device. So, executing this call in the exit routine caused the structure for this device to go away after 5 calls. So for now this problem is solved.
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I have a custom windows kernel driver I have compiled. I sign it with a test cert, create the cat file from the cdf, stamp the inx into a inf file, then load it with pnputil. I then create a software device with SwDeviceCreate so the OS will pair my driver and the driver. This works fine.
The problem is if i screw up something in the compilation and get something like an error code 39 (viewable in device manager), I do not see that error. Instead the OS seems to try to fix the error by loading the previously working version of the driver. In order to see that error, I have to purge the driver and device using pnputil /d oem42.inf along with a pnputil /remove-device, then restart my PC, that seems to fix the issue. This is difficult because it means i have to restart my PC every time i run a test. I know crashing a kernel driver can cause a panic anyway and cause me to restart, but there seems to be instances where this is not the case and the OS tries to rectify the issue without me (as it probably should).
So my question is this. Is there a way to completely purge my driver without a complete restart in-between installations/tests so I can correctly break it. I know I am suppose to use another machine and remote debug kernel drivers, but i do not have access to another machine right now that can support windows 11.
I have code that opens a libusb device, does some asynchronous transfers, and then quits. Sometimes the cleanup code at the end works out and I can re-run the program without problems, but other times
libusb_cancel_transfer returns LIBUSB_ERROR_PIPE and thereafter the device does not appear in the list returned by libusb_get_device_list in any subsequent execution of the program.
The problem can be recovered from by unplugging the device and reinserting into the same port, but that's not acceptable. I need at the very least some way to recover from the bad state in software, but ideally this shouldn't ever happen.
In case this problem could be platform related, I'm running MacOSX 10.9.5 and the program is C++ built with the llvm compiler.
I have discovered that I was inadvertently submitting control transfers whose setup packets were uninitialized memory. (Used the wrong size constant.) When I stopped doing that, the problem no longer occurred.
I am programming a pci device with verilog and also writing its driver,
I have probably inserted some bug in the hardware design and when i load the driver with insmod the kernel just gets stuck and doesnt respond. Now Im trying to figure out what's the last driver code line that makes my computer stuck. I have inserted printk in all relevant functions like probe and init but non of them get printed.
What other code is running when i use insmod before it gets to my init function? (I guess the kernel gets stuck over there)
printks are often not useful debugging such a problem. They are buffered sufficiently that you won't see them in time if the system hangs shortly after printk is called.
It is far more productive to selectively comment out sections of your driver and by process of elimination determine which line is the (first) problem.
Begin by commenting out the entire module's init section leaving only return 0;. Build it and load it. Does it hang? Reboot system, reenable the next few lines (class_create()?) and repeat.
From what you are telling, it is looks like that Linux scheduler is deadlocking by your driver. That's mean that interrupts from the system timer doesn't arrive or have a chance to be handled by kernel. There are two possible reasons:
You hang somewhere in your driver interrupt handler (handler starts its work but never finish it).
Your device creates interrupts storm (Device generates interrupts too frequently as a result your system do the only job -- handling of your device interrupts).
You explicitly disable all interrupts in your driver but doesn't reenable them.
In all other cases system will either crash, either oops or panic with all appropriate outputs or tolerate potential misbehavior of your device.
I guess that printk won't work for such extreme scenario as hang in kernel mode. It is quite heavy weight and due to this unreliable diagnostic tool for scenarios like your.
This trick works only in simpler environments like bootloaders or more simple kernels where system runs in default low-end video mode and there is no need to sync access to the video memory. In such systems tracing via debugging output to the display via direct writing to the video memory can be great and in many times the only tool that can be used for debugging purposes. Linux is not the case.
What techniques can be recommended from the software debugging point of view:
Try to review you driver code devoting special attention to interrupt handler and places where you disable/enable interrupts for synchronization.
Commenting out of all driver logic with gradual uncommenting can help a lot with localization of the issue.
You can try to use remote kernel debugging of your driver. I advice to try to use virtual machine for that purposes, but I'm not aware about do they allow to pass the PCI device in the virtual machine.
You can try the trick with in-memory tracing. The idea is to preallocate the memory chunk with well known virtual and physical addresses and zeroes it. Then modify your driver to write the trace data in this chunk using its virtual address. (For example, assign an unique integer value to each event that you want to trace and write '1' into the appropriate index of bytes array in the preallocated memory cell). Then when your system will hang you can simply force full memory dump generation and then analyze the memory layout packed in the dump using physical address of the memory chunk with traces. I had used this technique with VmWare Workstation VM on Windows. When the system had hanged I just pause a VM instance and looked to the appropriate .vmem file that contains raw memory latout of the physical memory of the VM instance. Not sure that this trick will work easy or even will work at all on Linux, but I would try it.
Finally, you can try to trace the messages on the PCI bus, but I'm not an expert in this field and not sure do it can help in your case or not.
In general kernel debugging is a quite tricky task, where a lot of tricks in use and all they works only for a specific set of cases. :(
I would put a logic analyzer on the bus lines (on FPGA you could use chipscope or similar). You'll then be able to tell which access is in cause (and fix the hardware). It will be useful anyway in order to debug or analyze future issues.
Another way would be to use the kernel crash dump utility which saved me some headaches in the past. But depending your Linux distribution requires installing (available by default in RH). See http://people.redhat.com/anderson/crash_whitepaper/
There isn't really anything that is run before your init. Bus enumeration is done at boot, if that goes by without a hitch the earliest cause for freezing should be something in your driver init AFAIK.
You should be able to see printks as they are printed, they aren't buffered and should not get lost. That's applicable only in situations where you can directly see kernel output, such as on the text console or over a serial line. If there is some other application in the way, like displaying the kernel logs in a terminal in X11 or over ssh, it may not have a chance to read and display the logs before the computer freezes.
If for some other reasons the printks still do not work for you, you can instead have your init function return early. Just test and move the return to later in the init until you find the point where it crashes.
It's hard to say what is causing your freezes, but interrupts is one of those things I would look at first. Make sure the device really doesn't signal interrupts until the driver enables them (that includes clearing interrupt enables on system reset) and enable them in the driver only after all handlers are registered (also, clear interrupt status before enabling interrupts).
Second thing to look at would be bus master transfers, same thing applies: Make sure the device doesn't do anything until it's asked to and let the driver make sure that no busmaster transfers are active before enabling busmastering at the device level.
The fact that the kernel gets stuck as soon as you install your driver module makes me wonder if any other driver (built in to kernel?) is already driving the device. I made this mistake once which is why i am asking. I'd look for the string "kernel driver in use" in the output of 'lspci' before installing the module. In any case, your printk's should be visible in dmesg output.
in addition to Claudio's suggestion, couple more debug ideas:
1. try kgdb (https://www.kernel.org/doc/htmldocs/kgdb/EnableKGDB.html)
2. use JTAG interfaces to connect to debug tools (these i think vary between devices, vendors so you'll have to figure out which debug tools you need to the particular hardware)
I made a device driver. But my system crashed at the moment when it was deleting the device object. I think the symbolic link was deleted and it crashed after it was trying to delete the device as I can't see the symbolic link in the Global.
How do I delete this device now. It also gives me a error popup(system cannot find the file specified Device\Mydriver) when I try to open the listed Mydriver under devices from Winobj.
I tried starting the driver's service again. I do get a handle back when opening the service. But it wont start now. giving the error value of Cannot find the file specified. I was working fine, i mean starting the driver before this crash.
I am a beginner with drivers and doing this to learn, please guide.
I have taken this from : Programming microsoft windows driver 2nd edition by woney
I hope this helps.
Removability of devices in a Plug and Play environment is the ultimate source of the early-unload problem
mentioned in the text. it’s your responsibility to avoid sending an IRP to a driver that might no longer be in memory
and to prevent the PnP manager from unloading a driver that’s still processing an IRP you’ve sent to that driver.
One aspect of how you fulfill that responsibility is shown in the text: take an extra reference to the file object
returned by IoGetDeviceObjectPointer around the call to IoCallDriver. In most drivers, you’ll probably need the
extra reference only when you’re sending an asynchronous IRP. In that case, the code that ordinarily
dereferences the file object is likely to be in some other part of your driver that runs asynchronously with the
call to IoCallDriver—say, in the completion routine you’re obliged to install for an asynchronous IRP. If you send
a synchronous IRP, you’re much more likely to code your driver in such a way that you don’t dereference the file
object until the IRP completes.
Use the interactive boot option and don't load the troublesome driver. Then you can experiment perhaps by adding diagnostic instrumentation to the driver or other debugging techniques to determine the underlying problem.
A possible cause of a CL_OUT_OF_RESOURCES error is that the card is being used to run a display (Ref). I have found, however, that I continue to get this error after disconnecting the display and it persists until I restart. Is there a command that will make the OpenCL resources available again?
CL_OUT_OF_RESOURCES is a common error to nVIDIA driver. And can be caused by:
Real out of resources (rare)
Reading an array that was used by a kernel that read/writed out of bounds. (typical)
Any other strange error that does not have an appropriate error code.
You are provably facing the second one, so, I would check the kernels.
EDIT: As you said that it happens until restart. Maybe you can check if you are deleting properly all the OpenCL objects. Events are very tricky and easy to leak some OpenCL memory.
How much memory are you trying to allocate, and how much does the card have on board? A video card driving a display has a certain amount of memory set aside for some operations. The driver may simply be reserving this memory and not caring if the display is gone till it is restarted.
On that note, it is possible to restart the video driver in Windows using devcon. On Linux, you could try an
lsmod | grep nvidia
and once you know the module name, perhaps an
rmmod
or
modprobe -r
I don't know if this will work on OSX.