Date: Fri, 21 Apr 2017 20:12:21 +0200
From: Borislav Petkov <bp@alien8.de>
To: "Baicar, Tyler" <tbaicar@codeaurora.org>
Cc: christoffer.dall@linaro.org, marc.zyngier@arm.com, pbonzini@redhat.com,
        rkrcmar@redhat.com, linux@armlinux.org.uk, catalin.marinas@arm.com,
        will.deacon@arm.com, rjw@rjwysocki.net, lenb@kernel.org,
        matt@codeblueprint.co.uk, robert.moore@intel.com, lv.zheng@intel.com,
        nkaje@codeaurora.org, zjzhang@codeaurora.org, mark.rutland@arm.com,
        james.morse@arm.com, akpm@linux-foundation.org,
        eun.taik.lee@samsung.com, sandeepa.s.prabhu@gmail.com,
        labbott@redhat.com, shijie.huang@arm.com, rruigrok@codeaurora.org,
        paul.gortmaker@windriver.com, tn@semihalf.com, fu.wei@linaro.org,
        rostedt@goodmis.org, bristot@redhat.com,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-acpi@vger.kernel.org, linux-efi@vger.kernel.org,
        Suzuki.Poulose@arm.com, punit.agrawal@arm.com, astone@redhat.com,
        harba@codeaurora.org, hanjun.guo@linaro.org, john.garry@huawei.com,
        shiju.jose@huawei.com, joe@perches.com, rafael@kernel.org,
        tony.luck@intel.com, gengdongjiu@huawei.com, xiexiuqi@huawei.com
Subject: Re: [PATCH V15 03/11] cper: add timestamp print to CPER status
 printing
Message-ID: <20170421181221.4qqfprbyljgv4ekb@pd.tnic>
References: <1492556723-9189-1-git-send-email-tbaicar@codeaurora.org>
 <1492556723-9189-4-git-send-email-tbaicar@codeaurora.org>
 <20170421122150.76cce2cfrt767glv@pd.tnic>
 <35cc4ae0-e8fa-fd3a-5d7f-243ed2e82ea0@codeaurora.org>
 <20170421172603.4574wonnm5tgvbcn@pd.tnic>
 <a20143dc-8daa-102b-d929-4d96f73353e3@codeaurora.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <a20143dc-8daa-102b-d929-4d96f73353e3@codeaurora.org>
User-Agent: NeoMutt/20170113 (1.7.2)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1119
Lines: 29

On Fri, Apr 21, 2017 at 12:08:43PM -0600, Baicar, Tyler wrote:
> The timestamp may still be useful when it is imprecise. In the polling case,
> you may only poll every minute or so, so the time may be useful.

Well, what is in the timestamp when !precise? Some random time or some
timestamp from a couple of seconds ago? How do you differentiate what
timestamp is bollocks and what is from a while ago?

Is the imprecise tstamp really close to the time the error happened or
pointing at 1970 - the beginning of unix time? :-)

I'm sure you've picked up by now that we don't trust the firmware one
bit.

> Also, I imagine there could be interrupt based errors happening much faster than the
> FW/OS handshake can happen. Maybe we can just use what I had before but also
> specify imprecise so that it is clear:
> 
>         printk("%s%ststamp: %02d%02d-%02d-%02d %02d:%02d:%02d\n", pfx,
>             (timestamp[3] & 0x1 ? "precise " : "imprecise "),
>              century, year, mon, day, hour, min, sec);

I guess.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.