linux-kernel - Re: [v5 PATCH] RISC-V: Fix unsupported isa string info.

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Message-ID: <491aa3fb2d08e283ecedb5c02f9555d10f458ecb.camel@wdc.com>
Date:   Sat, 14 Sep 2019 04:07:55 +0000
From:   Atish Patra <Atish.Patra@....com>
To:     "palmer@...ive.com" <palmer@...ive.com>,
        "hch@...radead.org" <hch@...radead.org>
CC:     "anup@...infault.org" <anup@...infault.org>,
        "paul.walmsley@...ive.com" <paul.walmsley@...ive.com>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "aou@...s.berkeley.edu" <aou@...s.berkeley.edu>,
        "johan@...nel.org" <johan@...nel.org>
Subject: Re: [v5 PATCH] RISC-V: Fix unsupported isa string info.

On Fri, 2019-09-13 at 13:47 -0700, Palmer Dabbelt wrote:
> On Mon, 09 Sep 2019 23:00:10 PDT (-0700), Christoph Hellwig wrote:
> > On Fri, Sep 06, 2019 at 11:27:57PM +0000, Atish Patra wrote:
> > > > Agreed. May be something like this ?
> > > > 
> > > > Let's say f/d is enabled in kernel but cpu doesn't support it.
> > > > "unsupported isa" will only appear if there are any unsupported
> > > > isa.
> > > > 
> > > > processor       : 3
> > > > hart            : 4
> > > > isa             : rv64imac
> > > > unsupported isa	: fd
> > > > mmu             : sv39
> > > > uarch           : sifive,u54-mc
> > > > 
> > > > May be I am just trying over optimize one corner case :) :).
> > > > /proc/cpuinfo should just print all the isa string. That's it.
> > > > 
> > > 
> > > Ping ?
> > 
> > Yes, I agree with the "dumb" reporting of all capabilities.
> 
> I agree: it looks like other architectures are passing info (ie, x86
> flags) 
> that isn't supported by userspace.  We have the ELF hwcap stuff for
> those who 
> want to tell which instructions they can run, so it's sane to just
> keep this 
> simple.

Great. That will simplify the code path as well. I will send a v6 with
the fixes.

-- 
Regards,
Atish