I simulate the fault disk using Fauly Injection (https://www.kernel.org/doc/Documentation/fault-injection/fault-injection.txt).
But the /sys/kernel/debug/fail_make_request/ path don't exist.
So how can I enable or install it?
The fault injection is not enabled in the default kernels provided by RHEL, while its only available on the debug kernels. Its best to talk to the Linux vendor for getting the debug kernel or supporting it enabled in the standard kernel.
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I am going through the CXL support in Linux Kernel and I found that there is no function or support for cxl.cache. I'm confused if the cache part is not yet implemented in linux kernel or if the kernel should not have access to the cache commands?
(I have seen up to the latest Kernel release, 5.19)
I have added some IOCTL calls to the existing cifs kernel module.
How do I ensure that the customized cifs module is supported with future kernel upgrades?
Also how to compile the customized cifs module for various Linux flavours ?
The customized kernel module runs with the current kernel version. But as soon as I upgrade my kernel, I cant use the customized Cifs module since it is compiled with the previous kernel version.
I dont want to compile the kernel module manually to be supported for every kernel upgrade
Once the Uboot loads the Linux kernel image (ZImage) onto the ram, it invokes it (could be using bootz, bootm or some other commands based on the type of the kernel Image) and then the control goes to booting the kernel. Does the uboot will be informed about the kernel boot result?, means, whether the kernel booting went through completely or got stuck in the middle because of errors?.
I looked at do_bootz, do_bootm_states and boot_selected_os api's in the uboot src code to see if there is any way to know about the final kernel boot result, but I couldn't able to figured it out.
Details:
U-boot Version: 2017.03-rc2
api's are available at: cmd/bootz.c and bootm.c files.
If any one in this community knows about it or have an idea about it, please explain to me or point me to the correct path.
Thanks in advance.
Regards
Vamsi Chagari
After bootm, booti, bootz transfer control to the kernel the memory formerly used by U-Boot will be reused by the operating system. As U-Boot is no longer in memory it cannot be informed about the operating system status.
If you use the bootefi command the U-Boot implementation of the UEFI runtime services stays in memory while the operating system is starting. The UEFI services can be called by the operating system. These include services relating to variables. One use of UEFI variables is the definition of the boot sequence.
Unfortunately UEFI variables are not yet completetly implemented in U-Boot (as of version v2018.07). They currently cannot be accessed after exiting boot services.
I have recently been attempting to create a GPIO Driver for SBC's using an Intel chipset that run Windows 8.1 and have begun testing it on an actual system. After loading the Driver and updating the Intel chipset I am using, the system appears to hang after loading the BIOS. Unfortunately, this disables my mouse, keyboard, and video, preventing me from entering BIOS or the boot manager.
While it is possible that the chipset update caused the system to become unbootable, it is highly unlikely considering we use that update for our other SBC's running the same chipset.
So my question: Is it possible for a Windows Kernel Mode driver to prevent a system from booting up past BIOS/POST?
I appreciate the help, since, clearly, I am no expert on this topic.
Yes, if your driver is being loaded at boot time it can prevent the booting of the OS and it will end up in BSOD(Blue screen of death) error with related bug check.
According to bugcheck displayed by the OS you can resolve the issues with your driver.
Or sometimes if its not giving any error and just hangs you can use WinDbg to check the bugcheck.
It depends on the error control of the driver service. Boot time drivers can also fail at any point. There is nothing special about the failure happening during boot. Instead, what is relevant under this scenario depends more on the ErrorControl value of the driver service which specifies how to proceed if it fails to load or initialize properly. A value of 3 (critical) would reboot the system to LKGC. Same rules apply to a win32 servic as well..
I use CentOS and it does not have support for L2TPv3 which was introduced in 2.6.35.
CentOS is at 2.6.32. How do I selectively patch just the L2TPv3 changes to my kernel?
Also, these are kernel modules. Would I need to run the modified kernel to be able to insmod these KOs?
Back porting features is a very non trivial task, not something that can easily be done casually. Thus, your best option is to look around whether somebody created the necessary patches for your kernel version.
Also, Linux kernel has no strict interface definitions when modules are concerned, thus it is very desirable that kernel and modules are compiled from the same source. Sometimes it is possible to successfully use "mismatched" modules with a given kernel, but rather frequently an attempt to do so results in various problems.
But if you will adventurous, try using modprobe -f. This will disable the module version checking and modprobe will try to squeeze the module in (even at a cost of crashing the system on spot).