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From:   Vineet Gupta <vineet.gupta1@synopsys.com>
To:     Eugeniy Paltsev <eugeniy.paltsev@synopsys.com>,
        "linux-snps-arc@lists.infradead.org" 
        <linux-snps-arc@lists.infradead.org>
CC:     "robh@kernel.org" <robh@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ARC: [hsdk] Make it easier to add PAE40 region to DTB
Thread-Topic: [PATCH] ARC: [hsdk] Make it easier to add PAE40 region to DTB
Thread-Index: AQHU6YjWxx0Wxr9B3kK5/52+iXhnUg==
Date:   Wed, 3 Apr 2019 16:44:32 +0000
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 <1554309241.2797.20.camel@synopsys.com>
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On 4/3/19 9:34 AM, Eugeniy Paltsev wrote:=0A=
>> -		reg =3D <0x80000000 0x40000000>;  /* 1 GiB */=0A=
>> +		reg =3D <0x0 0x80000000 0x0 0x40000000>;  /* 1 GB lowmem */=0A=
>> +		/*     0x1 0x00000000 0x0 0x40000000>;     1 GB highmem */=0A=
> Could you please get rid of comment with reference for PAE40/HIGHMEM regi=
on in this patch?=0A=
> It gives wrong expectations that if we uncomment it and enable PAE40 in c=
onfig we'll get working system.=0A=
> But it isn't true - we also need to remap AXI apertures appropriately.=0A=
=0A=
Well I didn't have to do any remapping for successfully running a cross gli=
bc=0A=
testsuite over ssh.=0A=
This was v5.1-rc1 + HIGHMEM+ PAE + patch to disable ioc + this patch for DT=
 update.=0A=
=0A=
Perhaps the remapping is needed when you are remapping DDR to 0 (for HIGHME=
M + !PAE)=0A=
=0A=
> Otherwise kernel will crush somewhere. Moreover kernel will crush for dif=
ferent reasons in case of launch=0A=
> via U-boot and via MDB (because we remap AXI apertures in U-boot for inte=
rnal purposes).=0A=
=0A=
This was all via mdb !=0A=
=0A=
> If you really want to keep this - I can send you patch with AXI apertures=
 remapping we need to apply firstly.=0A=
=0A=
Well I can drop the last commented line but I don't want to do wholesale ch=
anges=0A=
to DT for enabling DT, so would liek to keep the rest of the patch anyways.=
=0A=
=0A=
But sure send over the AXI remapping stuff - is that described in hsdk spec=
s ?=0A=
=0A=
-Vineet=0A=