Re: [PATCH v3 1/3] powerpc/powernv: convert codes returned by OPAL calls

On Mon, 2015-03-30 at 08:37 +0200, Cedric Le Goater wrote:

On 03/30/2015 04:05 AM, Michael Ellerman wrote:

quoted

On Fri, 2015-03-27 at 17:39 +0100, Cédric Le Goater wrote:

quoted

OPAL has its own list of return codes. The patch provides a translation
of such codes in errnos for the opal_sensor_read call, and possibly 
others if needed.

+	case OPAL_UNSUPPORTED:		return -ENOSYS;

You shouldn't use ENOSYS here, that should only ever mean "no such syscall",
otherwise you get very confusing results like read() returning ENOSYS.

Indeed. How about ENODEV then ? 

That can also be confusing from userspace.

I think it's probably best just to use EIO, as far as userspace is concerned if
the kernel lets it call an unsupported OPAL routine that is more or less a
kernel bug.

cheers