| Message ID | 1341367375-11467-9-git-send-email-swarren@wwwdotorg.org |
|---|---|
| State | Changes Requested |
| Delegated to: | Tom Rini |
| Headers | show |
On 07/03/2012 08:09 PM, Naren (Narendra) Sankar wrote: > This should not be hard-coded. > > The current board has 256MB but still allows the VC to use different RAM configuration splits. So the u-boot/Linux partition can get more than 128MB. While that's true, I believe there's currently no runtime API available to retrieve the memory split information. When such an API is available, we can remove the hard-coded limit and use the API instead. Such an API has been requested; see: https://github.com/raspberrypi/firmware/issues/47 > And it is possible to support up to 1GB of DRAM on this platform. The hard-coding is in a location specific to the Raspberry-Pi model B. So, it doesn't impose any restrictions on any other boards using the same SoC. While the BCM2835 SoC may allow more memory, the RPi B specifically only supports exactly 256MB.
diff --git a/board/raspberrypi/rpi_b/rpi_b.c b/board/raspberrypi/rpi_b/rpi_b.c index 26df74b..688b0aa 100644 --- a/board/raspberrypi/rpi_b/rpi_b.c +++ b/board/raspberrypi/rpi_b/rpi_b.c @@ -21,7 +21,7 @@ DECLARE_GLOBAL_DATA_PTR; int dram_init(void) { - gd->ram_size = SZ_256M; + gd->ram_size = CONFIG_SYS_SDRAM_SIZE; return 0; } diff --git a/include/configs/rpi_b.h b/include/configs/rpi_b.h index b9595f9..9f74731 100644 --- a/include/configs/rpi_b.h +++ b/include/configs/rpi_b.h @@ -36,6 +36,13 @@ #define CONFIG_NR_DRAM_BANKS 1 #define CONFIG_SYS_TEXT_BASE 0x00008000 #define CONFIG_SYS_SDRAM_BASE 0x00000000 +/* + * The board really has 256M. However, the VC (VideoCore co-processor) shares + * the RAM, and uses a configurable portion at the top. We tell U-Boot that a + * smaller amount of RAM is present in order to avoid stomping on the area + * the VC uses. + */ +#define CONFIG_SYS_SDRAM_SIZE SZ_128M #define CONFIG_SYS_UBOOT_BASE CONFIG_SYS_TEXT_BASE #define CONFIG_SYS_INIT_RAM_SIZE SZ_4K #define CONFIG_SYS_INIT_SP_ADDR (CONFIG_SYS_SDRAM_BASE + \
The board really has 256M. However, the VC (VideoCore co-processor) shares the RAM, and uses a configurable portion at the top. We tell U-Boot that a smaller amount of RAM is present in order to avoid stomping on the area the VC uses. Extracted from work by Oleksandr Tymoshenko <gonzo@bluezbox.com>. Signed-off-by: Stephen Warren <swarren@wwwdotorg.org> --- board/raspberrypi/rpi_b/rpi_b.c | 2 +- include/configs/rpi_b.h | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-)