Linux RAM Memory Map

The RidgeRun SDK bspconfig file contains the entries needed to determine the Linux RAM memory map. The physical start of SDRAM address is 0x80000000.

In the table below, the CONFIG_ has been left off the entries taken from the bspconfig file.

Region	Start Address Formula	Start Address (Example Value)	Size Formula	Size (Example Value)	Notes
Kernel	BSP_ARCH_SDRAM_BASE	0x80000000	KCL mem	0x09C00000 mem=156M	The kernel executable is included in this region. The kernel executable starts at 0x80008000 with the first 32K (0x8000) used by the kernel for the initial MMU table. Look in `kernel/linux-2.6.32.17-psp03.01.01.39/arch/arm/kernel/head.S` for details on the setup of the initial MMU table.
Capture buffer	After kernel	0x89C00000	KCL vpfe_capture.cont_bufsize	0x00C00000 12Mbytes	Calculate the size to reserve for the capture buffers based on the maximum image resolution and how many buffers you require. height * width * 2 bytes/pixel * number_of_buffers 1920 * 1088 * 2 * 3 Round amount to the next 4MB boundary. 1088 is used instead of 1080 do due hardware requiring the width to be divisible by 32. 2 bytes/pixel is used for UYVY encoding.
Display buffer	After kernel + KCL vpfe_capture.cont_bufoffset	0x8A800000	KCL davinci_display.cont2_bufsize	0x00D00000	Calculate the size to reserve for the display buffers based on the maximum image resolution and how many buffers you require. Round amount to the next 4096 boundary.
CMEM	After kernel + KCL vpfe_capture.cont_bufsize + davinci_display.cont2_bufsize	0x8B500000	Rest of SD RAM BSP_ARCH_SDRAM_SIZE minus amount used above	0x04B00000	CMEM can use all the remaining SD RAM above the kernel and display and capture buffers.

Notes:

KCL is the kernel command line, also called cmdline. You can retrieve the KCL using
```
cat /proc/cmdline
```
. An example kernel command line used for the values above is:

davinci_enc_mngr.ch0_output=COMPONENT davinci_enc_mngr.ch0_mode=1080I-30 davinci_display.cont2_bufsize=13631488 vpfe_capture.cont_bufoffset=13631488 vpfe_capture.cont_bufsize=12582912 video=davincifb:osd1=0x0x8:osd0=1920x1080x16,4050K@0,0:vid0=off:vid1=off console=none dm365_imp.oper_mode=0 mem=156M ubi.mtd=FS root=ubi0:rootfs rootfstype=ubifs mtdparts=davinci_nand.0:4096k(UBOOT),4736k(KERNEL),204800k(FS) davinci_emac.ethaddr=40:61:86:e9:82:22

For video capture, each pixel is typically in NV12 which takes 2 bytes / pixel.