Available memory in Linux

ranchu

Guru 20755 points

Hello,

I am using bootargs with mem=128M, (bootargs=console=ttyO0,115200n8 ip=10.0.0.2 root=/dev/mtdblock5 rw rootfstype=jffs2 rootdelay=15 rw earlyprintk notifyk.vpssm3_sva=0xBFD00000 mem=128M ddr_mem=512M vram=50M) but on showing available memory with:

cat /proc/meminfo

I see that only 78M is available.

Is it because of vram=50M ?

Must we use vram ?

Regards,

Ran

over 10 years ago

0 Margarita Gashova over 10 years ago

TI__Guru* 80190 points

Hello,

MemTotal: Total usable ram (i.e. physical ram minus a few reserved
bits and the kernel binary code)

Try : "dmesg|grep Memory" this will give you better info for available and reserved one.

Best Regards,
Margarita

0 Pavel Botev over 10 years ago

TI__Guru**** 170625 points

Ran,

See also the below pointer:

processors.wiki.ti.com/.../TI81XX_PSP_04.04.00.02_Feature_Performance_Guide

BR
Pavel

0 ranchu over 10 years ago in reply to Pavel Botev

Guru 20755 points

Hi Pavel,

Thank you very much for the pointer, it helps.
It says "Note: Around 50MB of RAM is reserved for FB driver by default hence you see total memory as 150MB when passing 'mem=200M'"
But where did we tell Linux to reserve 50M for FB driver ? (I don't see it in bootargs)

Thank you very much,
Ran

0 Pavel Botev over 10 years ago in reply to ranchu

TI__Guru**** 170625 points

Ran,

I think the vram is used to allocate the frame buffer (FB) driver, vram=50M -> /dev/fbx

http://processors.wiki.ti.com/index.php/TI81XX_PSP_VPSS_Video_Driver_User_Guide#Command_Line_arguments

0 ranchu over 10 years ago in reply to Pavel Botev

Guru 20755 points

Hi Pavel,

That make sense, but in my bootargs, I removed the verm=50:
(I also validate it linux with /cat/cmdline).
But still see that 50M are missing.
Do you find the same issue in your boards too when removing the vram parameters ?

Regards,
Ran

0 Pavel Botev over 10 years ago in reply to ranchu

TI__Guru**** 170625 points

Ran,

The same at my side. I always have 50M reserved with and without using vram=50M. And this memory is reserved for the FB driver. I see our Linux team provide you some hints in the Linux forum:

e2e.ti.com/.../397854

BR
Pavel

0 Margarita Gashova over 10 years ago in reply to ranchu

TI__Guru* 80190 points

Hello,

menuconfig:

                               --- TI81XX Video Processing Subsystem (EXPERIMENTAL)
                                (50) VRAM size (MB)
                                [*]   Debug support
                                <M>   TI81XX frame buffer support (EXPERIMENTAL) --->

Try to change it here and rebuild.

Let us know.

Best Regards,

Margarita

0 ranchu over 10 years ago in reply to Margarita Gashova

Guru 20755 points

Hi Margarita, Pavel,

Thank you very much.
The config file, seems to solve the issue.

Best Regard,
Ran

Processors

Processors forum

Available memory in Linux