Reserving a memory block at kernel start


I would like to use the extlinux.conf APPEND section to reserve a specific chunk of memory that to be used by my driver. It is a limitation of my FPGA design that I need a specific location to be used for PCIe.

Can someone advise whether this is feasible using the “memmap” APPEND option ( for example memmap=1G$38000000 ) in my extlinux.conf or if there is a better way?

From my experiments so far, it seems that memmap is not being accepted by the kernel.

uname -a
Linux tegra-ubuntu-1 3.10.96-tegra #1 SMP PREMPT Wed Nov 9 19:42:57 PST 2016 aarch64 aarch64 aarch64 GNU/Linux


This my extlinux.conf edits:

DEFAULT primary

MENU TITLE p2371-2180 eMMC boot options

LABEL primary
MENU LABEL primary kernel
LINUX /boot/Image
INITRD /boot/initrd
FDT /boot/tegra210-jetson-tx1-p2597-2180-a01-devkit.dtb
APPEND fbcon=map:0 console=tty0 console=ttyS0,115200n8 androidboot.modem=none androidboot.serialno=P2180A00P00940c003fd tegraid= ddr_die=2048M@2048M ddr_die=2048M@4096M section=256M memtype=0 usb_port_owner_info=0 lane_owner_info=0 emc_max_dvfs=0 touch_id=0@63 video=tegrafb no_console_suspend=1 debug_uartport=lsport,0 earlyprintk=uart8250-32bit,0x70006000 maxcpus=4 usbcore.old_scheme_first=1 lp0_vec={lp0_vec} nvdumper_reserved={nvdumper_reserved} core_edp_mv=1125 core_edp_ma=4000 gpt android.kerneltype=normal androidboot.touch_vendor_id=0 androidboot.touch_panel_id=63 androidboot.touch_feature=0 androidboot.bootreason=pmc:software_reset,pmic:0x0 net.ifnames=0 root=/dev/mmcblk0p1 rw rootwait memmap=1G$0x4000000