seL4::arm64::armv8::Write to processor register is causing halt in user space

New to seL4
1

Hi All,
I am trying to write a user space driver under “util_lib” folder for my latest seL4 port on arm64 cortexA53 based h/w. There are memory mapped registers which i am trying to access.
The read to those register succeeds but write to those register gives fault.

Below are the function used used

gpt->gpt_map = (volatile struct gpt_map *)ps_pmem_map(&gpt->io_ops, pmem, false, PS_MEM_NORMAL);
if (gpt->gpt_map == NULL) {
ZF_LOGE(“Failed to map in registers for the GPT”);
return EIO;
}

gpt->gpt_map->cr = 0;

The error generated during write is:
"halting…
Kernel entry via Unknown syscall, word: 3"

Can you please suggest as what can cause this issue …

Reagrds,
Misbah

2

If you write to read-only device registers, you may get an asynchronous abort via SError, which seL4 handles by halting the kernel if KernelAArch64SErrorIgnore is disabled.

(Yes, that’s stupid, but problem is that SError could be caused by anything.)