[RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions

On Monday 23 November 2015 12:38:47 Stephen Boyd wrote:

On 11/23, Arnd Bergmann wrote:

quoted

On Monday 23 November 2015 09:14:39 Christopher Covington wrote:

quoted

On 11/23/2015 03:15 AM, Arnd Bergmann wrote:
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.

arch/arm/boot/dts/qcom-apq8084.dtsi exists in the mainline
kernel. We support more than what's in the Kconfig language
under mach-qcom.

Ok, cool. I'm sometimes confused by the model numbers, could you
do a separate patch to update the Kconfig help text?

And yes LPAE is supported by apq8084 (as is
IDIV). Here's the /proc/cpuinfo on that device.
# cat /proc/cpuinfo
processor       : 0
model name      : ARMv7 Processor rev 1 (v7l)
BogoMIPS        : 38.40
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm

Ok.

quoted

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

Krait supports IDIV for all versions. Scorpion doesn't support
IDIV or lpae. Here's the output of /proc/cpuinfo on that device. 

# cat /proc/cpuinfo
processor       : 0
model name      : ARMv7 Processor rev 2 (v7l)
BogoMIPS        : 13.50
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpd32
CPU implementer : 0x51
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0x02d
CPU revision    : 2

Ok, that leaves just one missing puzzle piece: can you confirm that
no supported Krait variant other than Krait 450 / apq8084 has LPAE?

	Arnd