Re: [PATCH] riscv: add S and U modes to ISA string

From: Palmer Dabbelt
Date: Sun Nov 11 2018 - 17:14:46 EST


On Sat, 10 Nov 2018 00:35:15 PST (-0800), me@xxxxxxxx wrote:
On 10.11.18 07:45, David Abdurachmanov wrote:

The patch adds the missing S and U modes.

This is the same patch I submitted earlier (see v2 here [1], based on
Palmer's feedback). Palmer stated that the "S" extension should not be
exposed to usermode.

Since two people arrived at the same solution, I wonder if the
supervisor mode should really be hidden from userspace, as it's about
the CPU information, not about the environment the calling code is
running as.

[1] https://lkml.org/lkml/2018/11/10/96

I still think S should be hidden from applications. This patch was fairly mechanical, so it probably just wasn't though about twice -- that's the problem with user ABI stuff, lots of times the obvious answer isn't the correct one :).

I'll take your second patch, I just haven't gotten around to actually fully reviewing patches yet as I'm still in my email triage phase.

Thanks!