# Re: \[PATCH v12 15/22\] selftests/vm: powerpc implementation to check support for pkey

- From: Dave Hansen \<hidden\>
- Date: 2018-03-16 22:26:19 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2018/03/5218938
- Thread: https://ratatoskr.run/linux-kselftest/2018/02/5195852/t.md

```text
On 02/21/2018 05:55 PM, Ram Pai wrote:
>  #define PAGE_SIZE (0x1UL << 16)
> -static inline int cpu_has_pku(void)
> +static inline bool is_pkey_supported(void)
>  {
> -	return 1;
> +	/*
> +	 * No simple way to determine this.
> +	 * lets try allocating a key and see if it succeeds.
> +	 */
> +	int ret = sys_pkey_alloc(0, 0);
> +
> +	if (ret > 0) {
> +		sys_pkey_free(ret);
> +		return true;
> +	}
> +	return false;
>  }

The point of doing this was to have a test for the CPU that way separate
from the syscalls.

Can you leave cpu_has_pkeys() in place?
```