Linux/DRA754: J6 with 4 GB RAM support [LPAE]

Ishaqe Ahamed

Intellectual 645 points

Part Number: DRA754

Tool/software: Linux

We need to support 4GB RAM in J6 Board.

Is Large Physical Address Extension (LPAE) support in linux kernel validated in J6 platforms?

What are the additional configuration required in bootloader/kernel to support LPAE so that we can use 4GB RAM.

We are using Processor SDK 03.01.00

over 7 years ago

0 Pavel Botev over 7 years ago

TI__Guru**** 170625 points

Hi Ishaqe,

PSDKLA 3.1 is based on kernel 4.4, and I see that 4GB DDR3 and LPAE are supported there, see below e2e post:
e2e.ti.com/.../2020130

Latest version of DRA75x TI EVM comes with 4GB DDR3 RAM (2GB on EMIF1, 2GB on EMIF2) and the settings used are:

dmm_lisa_map_0 = 0x0
dmm_lisa_map_1 = 0x0
dmm_lisa_map_2 = 0x80740300
dmm_lisa_map_3 = 0xFF020100

See also if the below e2e thread will be in help:
e2e.ti.com/.../562675

Regards,
Pavel

0 Ishaqe Ahamed over 7 years ago

Intellectual 645 points

Hi,
Is there a performace impact if we enable LPAE ?
Have you measured the performance impact with system LPAE enabled and disabled ?

0 Pavel Botev over 7 years ago in reply to Ishaqe Ahamed

TI__Guru**** 170625 points

Ishaqe,

I made a search but I can not locate such document. What I was able to find is the below document, have a look:

www.ti.com/.../sprac46.pdf

Regards,
Pavel

0 Ishaqe Ahamed over 7 years ago in reply to Pavel Botev

Intellectual 645 points

Hi Pavel,

What is the performance impact of LPAE ?

Is it related to MMU only ?

Regards,

Ishaqe

0 Pavel Botev over 7 years ago in reply to Ishaqe Ahamed

TI__Guru**** 170625 points

Ishaqe,

As LPAE and MMU are entirely documented in the ARM Cortex-A15 MPCore documentation, what I can suggest you to check the ARM documentation about that. If the question remains unanswered (after reading) you can contact the ARM support team.

Regards,
Pavel

0 Pavel Botev over 7 years ago in reply to Pavel Botev

TI__Guru**** 170625 points

Ishaqe,

There is update from the PSP team:

e2e.ti.com/.../2094902

Regards,
Pavel

0 Ishaqe Ahamed over 6 years ago in reply to Pavel Botev

Intellectual 645 points

Hi,

Could you please share the DTB and the defconfig file for J6 EVM with 4GB RAM support(LPAE).

Is it supported in PSDK 3.01 Release ?

Reagrds,

Ishaqe

0 Pavel Botev over 6 years ago in reply to Ishaqe Ahamed

TI__Guru**** 170625 points

Ishaqe,

Ishaqe Ahamed said:
Could you please share the DTB and the defconfig file for J6 EVM with 4GB RAM support(LPAE).

These files are available with the PSDKLA 3.1

ti-processor-sdk-linux-automotive-dra7xx-evm-03_01_00_03/board-support/linux/arch/arm/configs/multi_v7_defconfig

ti-processor-sdk-linux-automotive-dra7xx-evm-03_01_00_03/board-support/linux/arch/arm/boot/dts/

For the correct DTS file usage, refer to the below wiki:

Regards,
Pavel

Processors

Processors forum

Linux/DRA754: J6 with 4 GB RAM support [LPAE]