fedisableexcept - Linux


fedisableexcept is a command designed primarily for kernel development and debugging. It allows advanced users to disable specific Floating-Point Exception (FPE) signals within a specified region of memory. This fine-grained control enables developers to isolate and troubleshoot issues related to FPEs in the kernel or user-space applications.


fedisableexcept [flags] [start_address] [end_address]


  • –filter (MASK): Specify a bitmask to select which exceptions to disable. See the FPU Control Word documentation for available masks. (Default: 0)
  • –debug (bool): Enable debugging output. (Default: false)
  • –help (-h): Display help text.
  • –version (-v): Display version information.


Disable all FPEs in a memory region:

fedisableexcept 0x01000000 0x02000000

Disable specific FPEs (e.g., invalid operation) in a region:

fedisableexcept --filter 0x00000001 0x01000000 0x02000000

Enable debugging output:

fedisableexcept --debug 0x01000000 0x02000000

Common Issues

Insufficient privileges: Ensure you run the command as root or with sufficient privileges to modify memory settings.

Invalid address range: Verify that the specified memory addresses are valid and accessible.


Debugging kernel FPEs:

fedisableexcept --debug 0x80000000 0x81000000

Testing FPE behavior in user-space applications:

fedisableexcept --filter 0x00000001 ./my_app

Related Commands

  • fpu: Manages the floating-point unit (FPU).
  • gdb: GDB debugger.