OMAP35x DVEVM Bootargs Options

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This page explains some of the important options in the bootargs and its impact on the extra memory the system consumes. The bootargs supports setting of up to 16 options as well as up to 512 characters from PSP SDK v2.00.01 onwards. Ensure that the overall size of the bootargs does not exceed 512 characters and the number of bootargs options does not exceed 16.

Enabling/Disabling Rotation

In the case of the OMAP35x DVEVM, the Linux PSP provides support for rotation. This needs to be enabled at the boot time but the rotation parameters can be specified during run time provided the rotation support is enabled at boot time. This needs to be specified in the bootargs. By default the bootargs mentioned in the OMAP35x DVEVM Getting Started Guide enables rotation. This is done by adding the following text to the bootargs.

For DVSDK version 3.01.00.01 onwards:

omapfb.rotate=1 omapfb.vrfb=y

For example,

setenv bootargs_nfs mem=88M console=ttyS0,115200n8 noinitrd ip=dhcp rw root=/dev/nfs nfsroot=<nfsserver_ip>:/home/<useracct>/workdir/filesys,nolock omapfb.rotate=1 omapfb.vrfb=y 

Till DVSDK version 3.00.02.44

omapfb.rotate=1 omapfb.rotate_type=1

For example,

setenv bootargs_nfs mem=88M console=ttyS0,115200n8 noinitrd ip=dhcp rw root=/dev/nfs nfsroot=<nfsserver_ip>:/home/<useracct>/workdir/filesys,nolock omapfb.rotate=1 omapfb.rotate_type=1 

To disable rotation simply remove the above options from the kernel bootargs.

Enabling/Disabling boot time allocation of memory for V4L2 driver buffers

In the case of the OMAP35x DVEVM, the Linux PSP provides support for boot time allocation of memory for the V4L2 driver buffers. This ensures that the V4L2 driver is guaranteed of the memory and prevents run time errors due to non-availability of memory. This needs to be specified in the bootargs. By default the bootargs mentioned in the OMAP35x DVEVM Getting Started Guide enable this static allocation. This is done by adding the following text to the bootargs.

omap_vout.vid1_static_vrfb_alloc=y 

For example,

setenv bootargs_nfs mem=88M console=ttyS0,115200n8 noinitrd ip=dhcp rw root=/dev/nfs nfsroot=<nfsserver_ip>:/home/<useracct>/workdir/filesys,nolock omap_vout.vid1_static_vrfb_alloc=y 

This is required to ensure that there are no page allocation errors while running the DVSDK demos with rotation enabled. If there is no memory available during run time, the V4L2 allocation of buffers for VRFB would fail, resulting in this error. Inclusion of the above statement would ensure avoidance of such problem while rotation is enabled.

To disable static allocation simply remove the above options from the kernel bootargs.

Enabling Support for Double Buffering for the OSD plane when rotation is enabled

In case you need support for double buffering in for the OSD plane when rotation is enabled, you need to append the option given in the box below to the bootargs for allocating the frame buffer memory. This is documented in the PSP user guide.

NOTE: This is only valid if rotation is enabled.

vram=20M omapfb.vram=20M

For example

setenv bootargs_nfs mem=88M console=ttyS0,115200n8 noinitrd ip=dhcp rw root=/dev/nfs nfsroot=<nfsserver_ip>:/home/<useracct>/workdir/filesys,nolock omapfb.rotate=1 omapfb.rotate_type=1 vram=20M omapfb.vram=20M omap_vout.vid1_static_vrfb_alloc=y

To disable double buffering simply remove the above options from the kernel bootargs.

Improving NFS speeds

If you are using NFS mount, or using NFS for development and the NFS server uses the UDP protocol for data transfers, there is a possibility that in some such setups you might see the NFS speeds to be slower than normal by more than a factor of 2. In such instances, please try adding proto=tcp option to the bootargs.

For example,

setenv bootargs_nfs    mem=88M console=ttyS0,115200n8 noinitrd ip=dhcp rw root=/dev/nfs nfsroot=<nfsserver_ip>:/home/<useracct>/workdir/filesys,nolock omapfb.rotate=1 omapfb.rotate_type=1 omap_vout.vid1_static_vrfb_alloc=y

For some network configurations where the DHCP server may give a different IP address after the kernel boots when the network is being initialized you may get messages like the one below

<5>nfs: server 192.168.247.79 not responding, still trying

nfs: server 192.168.247.79 not responding, still trying

<5>nfs: server 192.168.247.79 not responding, still trying 

nfs: server 192.168.247.79 not responding, still trying 

<5>nfs: server 192.168.247.79 OK 

nfs: server 192.168.247.79 OK 

<5>nfs: server 192.168.247.79 OK 

nfs: server 192.168.247.79 OK

In this case you should remove the proto=tcp option and fall back to booting using UDP.

Setting the MPU Rate from bootargs

In the case of the OMAP35x DVEVM, the Linux PSP provides support for boot time allocation of mpurate. This needs to be specified in the bootargs. This is done by adding the following text to the bootargs.

mpurate=600

User can specify appropiate mpurate.By default the mpurate is set as 500.