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Questions tagged [usermode]

68 questions
14
votes
1 answer

Difference between processes running in kernel mode and running as root?

I am aware of the difference between a process running in user mode and one running in kernel mode (based on access restrictions, access to hardware etc.). But just out of curiosity, what is the difference between a process running in kernel mode…
Legend
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0 answers

Windows User Mode Scheduler (UMS) Retired?

I just came around the following post which seems to say that the user mode scheduler which was introduced with Windows 7 is (going to be) retired? Don McCrady, Microsoft: As you may know from reading other forum entries here, the UMS scheduler is…
ronag
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2 answers

Executing a user-mode executable from kernel-mode

I'm building a HW-simulator for our driver team. Now, the simulator is devided in to 2 modules: First module runs inside the driver, in kernel mode and that's where the main interface between the driver and the HW-Simulator. Second module is an…
eladidan
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What is the main difference between drivers and user applications?

I know that user applications can run only in user mode, which is for system security. On the contrary most drivers run in kernel mode, to access I/O devices. Nevertheless some driver run in user mode, but are allowed to access I/O devices. So I…
user1289
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How to add user to a group without usermod?

Is it possible to add a user to a group without usermod? I'm working on embedded Linux 3.14.52 and I don't have the usermod command line. If it is not possible, how add this command to kernel with Buildroot?
M.Ferru
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How to call usermode from Windows kernel?

I'd like to call my app from my driver when an interesting event happens in the Windows kernel. I need to be able to pass at least 4 bytes of data back to user mode. How to achieve this? These events might happen quite, but not too, often, so I…
Raimo Helminen
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4 answers

C and resource protection in memory

When we compile a C program, it just generates some machine-understandable code. This code can directly run on the hardware, telling from this question. So my questions are: If a C program can directly run on the hardware, how can the kernel handle…
shiv garg
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Is there a difference in dt nt!_TEB and dt ntdll!_TEB?

I can dump types from an arbitrary module using dt modulename!type In some cases I saw e.g. dt nt!_TEB (and it works) although the module is called ntdll: 0:001> lm m nt start end module name 0:001> lm m ntdll start …
Thomas Weller
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4
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5 answers

switching to user stack in kernel dumps

Is there a way to switch to user mode of a particular process in a kernel dump while doing postmortem debugging ? I remember doing this while live debugging using the .process command.
user3279954
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Why driver in kernel mode must be very careful about directly reading from or writing to addresses in user space?

From msdn: Drivers that run in kernel mode must be very careful about directly reading from or writing to addresses in user space. This scenario illustrates why. A user-mode program initiates a request to read some data from a device. The program…
Nusrat Nuriyev
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Implementing User Mode and Kernel Mode Switching in 64 bit UEFI OS

I am writing a 64 Bit UEFI OS ( GNU-EFI - Bootloader ). I am wondered about User Mode and Kernel Mode in OS, I have to Implement User Mode and Kernel Mode in My OS, I found some on the Internet but It won't works for me ( I thinks it is because of…
user16028858
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1 answer

User mode driver with NDIS

Windows Filtering Platform provides API to develop both Kernel mode and User mode network filter driver. Is it possible to develop User mode Network filter driver on NDIS using Windows API?
Avinash Kumar Ranjan
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how to redirect stdout of a command from kernel space

I need to redirect stdout of a command invoked from kernel space using the linux usermode helper api. Using "echo" commmand as an example below. This does NOT work. static int umh_helper() { struct subprocess_info *sub_info; char *argv[] =…
anglee
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using arm LDM instruction to transfer data into user mode registers

I'm trying to restore user mode registers from svc mode on a cortex-a5 chip by using LDM instruction. I referred a technical guide for instruction LDM, the syntax is: LDM{addr_mode}{cond} Rn{!},reglist{^} '^' if specified (in a mode other than…
user3197437
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How do I get user-mode breakpoints to hit in windbg while kernel debugging?

I'm having trouble getting user mode breakpoints to hit in windbg when I am kernel debugging. I know that I have to be in the target process's context to set a user mode breakpoint, but that still doesn't seem to work reliably. Sometimes it works,…
R. Alabaster
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