Commit 56e45ea4 authored by Andre Przywara's avatar Andre Przywara Committed by Will Deacon
Browse files

arm: fdt: add stdout-path to /chosen node

The DT spec describes the stdout-path property in the /chosen node to
contain the DT path for a default device usable for outputting characters.
The Linux kernel uses this for earlycon (without further parameters),
other DT users might rely on this as well.

Add a stdout-path property pointing to the "serial0" alias, then add an
aliases node at the end of the FDT, containing the actual path. This
allows the FDT generation code in hw/serial.c to set this string.

Even when we use the virtio console, the serial console is still there
and works, so we can expose this unconditionally. Putting the virtio
console path in there will not work anyway.

Signed-off-by: Andre Przywara's avatarAndre Przywara <>
Signed-off-by: default avatarWill Deacon <>
parent 04d604b6
......@@ -142,6 +142,7 @@ static int setup_fdt(struct kvm *kvm)
_FDT(fdt_property_u64(fdt, "kaslr-seed", kvm->cfg.arch.kaslr_seed));
_FDT(fdt_property_string(fdt, "stdout-path", "serial0"));
/* Initrd */
if (kvm->arch.initrd_size != 0) {
......@@ -207,6 +208,15 @@ static int setup_fdt(struct kvm *kvm)
_FDT(fdt_property_cell(fdt, "migrate", fns->migrate));
if (fdt_stdout_path) {
_FDT(fdt_begin_node(fdt, "aliases"));
_FDT(fdt_property_string(fdt, "serial0", fdt_stdout_path));
fdt_stdout_path = NULL;
/* Finalise. */
......@@ -366,6 +366,9 @@ static bool serial8250_in(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port,
char *fdt_stdout_path = NULL;
void serial8250_generate_fdt_node(struct ioport *ioport, void *fdt,
......@@ -383,6 +386,12 @@ void serial8250_generate_fdt_node(struct ioport *ioport, void *fdt,
snprintf(dev_name, DEVICE_NAME_MAX_LEN, "U6_16550A@%llx", addr);
if (!fdt_stdout_path) {
fdt_stdout_path = malloc(strlen(dev_name) + 2);
/* Assumes that this node is a child of the root node. */
sprintf(fdt_stdout_path, "/%s", dev_name);
_FDT(fdt_begin_node(fdt, dev_name));
_FDT(fdt_property_string(fdt, "compatible", "ns16550a"));
_FDT(fdt_property(fdt, "reg", reg_prop, sizeof(reg_prop)));
......@@ -25,6 +25,8 @@ enum irq_type {
extern char *fdt_stdout_path;
/* Helper for the various bits of code that generate FDT nodes */
#define _FDT(exp) \
do { \
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