From: Arnd Bergmann <arnd@arndb.de>
To: Christopher Covington <cov@codeaurora.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>,
        Russell King - ARM Linux <linux@arm.linux.org.uk>,
        Peter Maydell <peter.maydell@linaro.org>,
        =?ISO-8859-1?Q?M=E5ns_Rullg=E5rd?= <mans@mansr.com>,
        "linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
        Stephen Boyd <sboyd@codeaurora.org>,
        lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        arm-mail-list <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions
Date: Mon, 23 Nov 2015 16:32:33 +0100
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On Monday 23 November 2015 09:14:39 Christopher Covington wrote:
> On 11/23/2015 03:15 AM, Arnd Bergmann wrote:
> > On Sunday 22 November 2015 21:36:45 Nicolas Pitre wrote:
> >> On Sun, 22 Nov 2015, Arnd Bergmann wrote:
> > 
> > Ok, thanks a lot! So the reporting in /proc/cpuinfo clearly matches
> > the actual features, and we can just treat this as no LPAE / no IDIV
> > for kernel compilation, as nobody ever seems to use THUMB2_KERNEL
> > in practice.
> > 
> > PJ4-MP is like Cortex-A15/A7/A12/A17 and supports both IDIV and LPAE,
> > which leaves the question whether Scorpion or Krait do the same as
> > well, or whether they are outliers and need a special configuration.
> 
> LPAE is only supported in the Krait 450.
> 
> http://www.anandtech.com/show/7537/qualcomms-snapdragon-805-25ghz-128bit-memory-interface-d3d11class-graphics-more
> 
> I'm pretty sure idiv support came earlier, but I don't have the
> specifics on hand.

I have seen that article, but didn't trust it as a canonical
source of information here.

If you can confirm that it's right, that would mean that we
don't support LPAE on mach-qcom, as the only SoC with Krait 450
seems to be APQ8084, and mainline Linux doesn't run on that.

The ones we do support are MSM8x60 (Scorpion), MSM8960
(Krait-without-number),and MSM7874 (Krait 400). Do those all
support IDIV but not LPAE?

	Arnd
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