1/* SPDX-License-Identifier: GPL-2.0+ */
2
3/* environment for Raspberry Pi boards */
4
5dhcpuboot=usb start; dhcp u-boot.uimg; bootm
6
7/* Environment */
8stdin=serial,usbkbd
9stdout=serial,vidconsole
10stderr=serial,vidconsole
11
12/* DFU over USB/UDC */
13#ifdef CONFIG_CMD_DFU
14dfu_alt_info=u-boot.bin fat 0 1;uboot.env fat 0 1;
15  config.txt fat 0 1;
16#ifdef CONFIG_ARM64
17dfu_alt_info+=Image fat 0 1
18#else
19dfu_alt_info+=zImage fat 0 1
20#endif
21#endif  /* CONFIG_CMD_DFU */
22
23/*
24 * Memory layout for where various images get loaded by boot scripts:
25 *
26 * I suspect address 0 is used as the SMP pen on the RPi2, so avoid this.
27 *
28 * Older versions of the boot firmware place the firmware-loaded DTB at 0x100,
29 * newer versions place it in high memory. So prevent U-Boot from doing its own
30 * DTB + initrd relocation so that we won't accidentally relocate the initrd
31 * over the firmware-loaded DTB and generally try to lay out things starting
32 * from the bottom of RAM.
33 *
34 * kernel_addr_r has different constraints on ARM and Aarch64.  For 32-bit ARM,
35 * it must be within the first 128M of RAM in order for the kernel's
36 * CONFIG_AUTO_ZRELADDR option to work. The kernel itself will be decompressed
37 * to 0x8000 but the decompressor clobbers 0x4000-0x8000 as well. The
38 * decompressor also likes to relocate itself to right past the end of the
39 * decompressed kernel, so in total the sum of the compressed and
40 * decompressed kernel needs to be reserved.
41 *
42 *   For Aarch64, the kernel image is uncompressed and must be loaded at
43 *   text_offset bytes (specified in the header of the Image) into a 2MB
44 *   boundary. The 'booti' command relocates the image if necessary. Linux uses
45 *   a default text_offset of 0x80000.  In summary, loading at 0x80000
46 *   satisfies all these constraints and reserving memory up to 0x02400000
47 *   permits fairly large (roughly 36M) kernels.
48 *
49 * scriptaddr and pxefile_addr_r can be pretty much anywhere that doesn't
50 * conflict with something else. Reserving 1M for each of them at
51 * 0x05400000-0x05500000 and 0x05500000-0x05600000 should be plenty.
52 *
53 * On ARM, both the DTB and any possible initrd must be loaded such that they
54 * fit inside the lowmem mapping in Linux. In practice, this usually means not
55 * more than ~700M away from the start of the kernel image but this number can
56 * be larger OR smaller depending on e.g. the 'vmalloc=xxxM' command line
57 * parameter given to the kernel. So reserving memory from low to high
58 * satisfies this constraint again. Reserving 1M at 0x05600000-0x05700000 for
59 * the DTB leaves rest of the free RAM to the initrd starting at 0x05700000.
60 * This means that the board must have at least 128MB of RAM available to
61 * U-Boot, more if the initrd is large.
62 *
63 * For compressed kernels, the maximum size is just under 32MB, with an area for
64 * decompression at 0x02000000 with space for 52MB, which is plenty for current
65 * kernels.
66 *
67 * limit bootm_size to 512MB so that all boot images stay within the bottom
68 * 512MB of memory
69 */
70bootm_size=0x20000000
71
72kernel_addr_r=0x00080000
73kernel_comp_addr_r=0x02000000
74kernel_comp_size=0x03400000
75scriptaddr=0x05400000
76pxefile_addr_r=0x05500000
77fdt_addr_r=0x05600000
78ramdisk_addr_r=0x05700000
79
80boot_targets=mmc usb pxe dhcp
81