Commit 69076dff authored by Neil Armstrong's avatar Neil Armstrong Committed by Tom Rini
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cmd: pxe: add support for FDT overlays

This adds support for specifying FDT overlays in an extlinux/pxelinux
configuration file.

Without this, there is no simple way to apply overlays when the kernel
and fdt is loaded by the pxe command.

This change adds the 'fdtoverlays' keyword for a label, supporting multiple
overlay files to be applied on top of the fdt specified in the 'fdt' or
'devicetree' keyword.

  label linux
    kernel /Image
    fdt /soc-board.dtb
    fdtoverlays /soc-board-function.dtbo
    append console=ttyS0,115200 root=/dev/mmcblk0p2 rootwait

This code makes usage of a new variable called fdtoverlay_addr_r used to load
the overlay files without overwritting anything important.

Cc: Tom Rini <>
Cc: Andre Heider <>
Cc: Jernej Škrabec <>
Cc: Jonas Karlman <>
Tested-by: default avatarJernej Škrabec <>
Reviewed-by: default avatarJernej Škrabec <>
Signed-off-by: Neil Armstrong <narmstrong@...
parent b5f09df2
Pipeline #6102 canceled with stages
in 15 minutes and 20 seconds
......@@ -13,6 +13,8 @@
#include <mapmem.h>
#include <lcd.h>
#include <net.h>
#include <fdt_support.h>
#include <linux/libfdt.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <errno.h>
......@@ -284,6 +286,9 @@ static void label_destroy(struct pxe_label *label)
if (label->fdtdir)
if (label->fdtoverlays)
......@@ -332,6 +337,92 @@ static int label_localboot(struct pxe_label *label)
return run_command_list(localcmd, strlen(localcmd), 0);
* Loads fdt overlays specified in 'fdtoverlays'.
static void label_boot_fdtoverlay(struct cmd_tbl *cmdtp, struct pxe_label *label)
char *fdtoverlay = label->fdtoverlays;
struct fdt_header *working_fdt;
char *fdtoverlay_addr_env;
ulong fdtoverlay_addr;
ulong fdt_addr;
int err;
/* Get the main fdt and map it */
fdt_addr = simple_strtoul(env_get("fdt_addr_r"), NULL, 16);
working_fdt = map_sysmem(fdt_addr, 0);
err = fdt_check_header(working_fdt);
if (err)
/* Get the specific overlay loading address */
fdtoverlay_addr_env = env_get("fdtoverlay_addr_r");
if (!fdtoverlay_addr_env) {
printf("Invalid fdtoverlay_addr_r for loading overlays\n");
fdtoverlay_addr = simple_strtoul(fdtoverlay_addr_env, NULL, 16);
/* Cycle over the overlay files and apply them in order */
do {
struct fdt_header *blob;
char *overlayfile;
char *end;
int len;
/* Drop leading spaces */
while (*fdtoverlay == ' ')
/* Copy a single filename if multiple provided */
end = strstr(fdtoverlay, " ");
if (end) {
len = (int)(end - fdtoverlay);
overlayfile = malloc(len + 1);
strncpy(overlayfile, fdtoverlay, len);
overlayfile[len] = '\0';
} else
overlayfile = fdtoverlay;
if (!strlen(overlayfile))
goto skip_overlay;
/* Load overlay file */
err = get_relfile_envaddr(cmdtp, overlayfile,
if (err < 0) {
printf("Failed loading overlay %s\n", overlayfile);
goto skip_overlay;
/* Resize main fdt */
fdt_shrink_to_minimum(working_fdt, 8192);
blob = map_sysmem(fdtoverlay_addr, 0);
err = fdt_check_header(blob);
if (err) {
printf("Invalid overlay %s, skipping\n",
goto skip_overlay;
err = fdt_overlay_apply_verbose(working_fdt, blob);
if (err) {
printf("Failed to apply overlay %s, skipping\n",
goto skip_overlay;
if (end)
} while ((fdtoverlay = strstr(fdtoverlay, " ")));
* Boot according to the contents of a pxe_label.
......@@ -534,6 +625,11 @@ static int label_boot(struct cmd_tbl *cmdtp, struct pxe_label *label)
goto cleanup;
if (label->fdtoverlays)
label_boot_fdtoverlay(cmdtp, label);
} else {
bootm_argv[3] = NULL;
......@@ -591,6 +687,7 @@ enum token_type {
......@@ -625,6 +722,7 @@ static const struct token keywords[] = {
{"fdt", T_FDT},
{"devicetreedir", T_FDTDIR},
{"fdtdir", T_FDTDIR},
{"fdtoverlays", T_FDTOVERLAYS},
{"ontimeout", T_ONTIMEOUT,},
{"ipappend", T_IPAPPEND,},
{"background", T_BACKGROUND,},
......@@ -1057,6 +1155,11 @@ static int parse_label(char **c, struct pxe_menu *cfg)
err = parse_sliteral(c, &label->fdtdir);
if (!label->fdtoverlays)
err = parse_sliteral(c, &label->fdtoverlays);
label->localboot = 1;
err = parse_integer(c, &label->localboot_val);
......@@ -43,6 +43,7 @@ struct pxe_label {
char *initrd;
char *fdt;
char *fdtdir;
char *fdtoverlays;
int ipappend;
int attempted;
int localboot;
......@@ -89,6 +89,9 @@ pxe boot
fdt_addr - the location of a fdt blob. 'fdt_addr' will be passed to bootm
command if it is set and 'fdt_addr_r' is not passed to bootm command.
fdtoverlay_addr_r - location in RAM at which 'pxe boot' will temporarily store
fdt overlay(s) before applying them to the fdt blob stored at 'fdt_addr_r'.
pxe file format
The pxe file format is nearly a subset of the PXELINUX file format; see
......@@ -148,6 +151,12 @@ kernel <path> - if this label is chosen, use tftp to retrieve the kernel
It useful for overlay selection in pxe file
(see: doc/uImage.FIT/overlay-fdt-boot.txt)
fdtoverlays <path> [...] - if this label is chosen, use tftp to retrieve the DT
overlay(s) at <path>. it will be temporarily stored at the
address indicated in the fdtoverlay_addr_r environment variable,
and then applied in the load order to the fdt blob stored at the
address indicated in the fdt_addr_r environment variable.
append <string> - use <string> as the kernel command line when booting this
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