On Tue, Jun 9, 2015 at 4:06 AM, Edward Wingate <edwinga...@gmail.com> wrote: > > I am using Yocto with meta-xilinx layer to create a distribution for a > custom Zynq 7000 board with 512MB RAM. In my uEnv, I'm loading the > kernel to 0x0010_0000, device tree to 0x0190_0000 and ramdisk image to > 0x0210_0000. > > Later in the boot process, I see this: > Loading Kernel Image ... OK > Loading Ramdisk to 1e16f000, end 1ed221fc ... OK > Loading Device Tree to 1e166000, end 1e16ef40 ... OK > > I'd like to restrict Linux to the lower 256MB out of 512MB of RAM. > When I add mem=256MB to boot arguments, the kernel doesn't boot. I > can specify "mem=" down to only 494M, I assume to get it just over > those 0x1exx_xxxx addresses. Any lower and the kernel doesn't boot. > Where do the 0x1exx_xxxx come from and how can I change those?
Those values are generated via u-boot based on the value of fdt_high and initrd_high which are set in the u-boot environment. (At least for Zynq) If you have a look at the default environment you will see them set to 0x20000000: http://git.denx.de/?p=u-boot.git;a=blob;f=include/configs/zynq-common.h;h=1a52e7d538261a9d36b078d61e00e60bf8918227;hb=HEAD#l217 You can override those environment variables with your uEnv.txt file, setting it to 0x10000000 will make sure they fdt/initrd is loaded into the first 256M. Regards, Nathan > > I also tried changing the memory in device tree. It was originally: > ps7_ddr_0: memory@0 { > device_type = "memory" > reg = <0x0 0x200000000>; > } > > I changed reg to <0x0 0x10000000> thinking this would limit the RAM > that Linux sees to the lower 256MB, but Linux still reports seeing all > 512MB of RAM. > > Can anyone point me to where else my configuration needs to change? > Thanks for your help. > > Edward > -- > _______________________________________________ > yocto mailing list > yocto@yoctoproject.org > https://lists.yoctoproject.org/listinfo/yocto -- _______________________________________________ yocto mailing list yocto@yoctoproject.org https://lists.yoctoproject.org/listinfo/yocto