[U-Boot] SDRAM

[U-Boot] SDRAM

[Naitik Amin]

I am using Altera SOC, under my includes, I have a file called 
/include/configs/socfpga_common.h

In this file, I have #define as below.
#define PHYS_SDRAM_1_SIZE               0x20000000

If this #define is set to 0x20000000, and uboot is compiled and loaded, 
the system when boots up into Linux, issuing free command under linux 
shows 512 MB. Which is *correct*. If I change that #define to 0x40000000, 
upon executing free command, linux shows 1G.

My questions, is how does this info from uboot reach kernel ?

Thanks,

[U-Boot] SDRAM

[Andreas Färber]

Hi,

Am 28.05.2015 um 23:49 schrieb Naitik Amin:
> I am using Altera SOC, under my includes, I have a file called 
> /include/configs/socfpga_common.h
> 
> In this file, I have #define as below.
> #define PHYS_SDRAM_1_SIZE               0x20000000
> 
> If this #define is set to 0x20000000, and uboot is compiled and loaded, 
> the system when boots up into Linux, issuing free command under linux 
> shows 512 MB. Which is *correct*. If I change that #define to 0x40000000, 
> upon executing free command, linux shows 1G.
> 
> My questions, is how does this info from uboot reach kernel ?

That will depend on your boot environment. :) The new mechanism would be
the Device Tree node /memory, if you are passing a .dtb file to
bootm/bootz. The legacy mechanism is so-called atags.

HTH,
Andreas

-- 
SUSE Linux GmbH, Maxfeldstr. 5, 90409 N?rnberg, Germany
GF: Felix Imend?rffer, Jane Smithard, Dilip Upmanyu, Graham Norton; HRB
21284 (AG N?rnberg)

[U-Boot] SDRAM

[Naitik Amin]

Hi Andreas, 
I thought of it too. I thought it was dtb all along. But all changed was 
below line, without even touching the dtb. I just replaced the uboot and I 
started to see 1G SDRAM. Thats why I got confused.



From:   Andreas F?rber <afaerber@suse.de>
To:     Naitik Amin <Naitik.Amin@ametek.com>, u-boot at lists.denx.de, 
Date:   06/05/2015 06:36 PM
Subject:        Re: [U-Boot] SDRAM



Hi,

Am 28.05.2015 um 23:49 schrieb Naitik Amin:
> I am using Altera SOC, under my includes, I have a file called 
> /include/configs/socfpga_common.h
> 
> In this file, I have #define as below.
> #define PHYS_SDRAM_1_SIZE               0x20000000
> 
> If this #define is set to 0x20000000, and uboot is compiled and loaded, 
> the system when boots up into Linux, issuing free command under linux 
> shows 512 MB. Which is *correct*. If I change that #define to 
0x40000000, 
> upon executing free command, linux shows 1G.
> 
> My questions, is how does this info from uboot reach kernel ?

That will depend on your boot environment. :) The new mechanism would be
the Device Tree node /memory, if you are passing a .dtb file to
bootm/bootz. The legacy mechanism is so-called atags.

HTH,
Andreas

-- 
SUSE Linux GmbH, Maxfeldstr. 5, 90409 N?rnberg, Germany
GF: Felix Imend?rffer, Jane Smithard, Dilip Upmanyu, Graham Norton; HRB
21284 (AG N?rnberg)