The /chosen FDT node is how the firmware indicates information about the kernel to the loader code. In a full boot chain this would come from something like a boot loader. However if we use the generic loader to load blobs into RAM before launching a hypervisor for example we can boot directly:
$QEMU $ARGS -kernel ~/xen.git/xen/xen \ -append "dom0_mem=1G,max:1G loglvl=all guest_loglvl=all" \ -device loader,addr=0x47000000,\ file=Image,\ len-fdt-compat=2,\ fdt-compat[0]='multiboot,,module',\ fdt-compat[1]='multiboot,,kernel',\ fdt-bootargs="root=/dev/mapper/vg0-root ro console=hvc0 earlyprintk=xen"
Note the ,, escapes required for the command line parser.
Signed-off-by: Alex Bennée alex.bennee@linaro.org --- include/hw/core/generic-loader.h | 4 +++ hw/core/generic-loader.c | 42 ++++++++++++++++++++++++++++++++ 2 files changed, 46 insertions(+)
diff --git a/include/hw/core/generic-loader.h b/include/hw/core/generic-loader.h index 19d87b39c8..98b0452430 100644 --- a/include/hw/core/generic-loader.h +++ b/include/hw/core/generic-loader.h @@ -39,6 +39,10 @@ struct GenericLoaderState { bool force_raw; bool data_be; bool set_pc; + + char **fdt_compat; + uint32_t fdt_compat_count; + char *fdt_bootargs; };
#define TYPE_GENERIC_LOADER "loader" diff --git a/hw/core/generic-loader.c b/hw/core/generic-loader.c index a242c076f6..8bd8a33e80 100644 --- a/hw/core/generic-loader.c +++ b/hw/core/generic-loader.c @@ -40,6 +40,8 @@ #include "qapi/error.h" #include "qemu/module.h" #include "hw/core/generic-loader.h" +#include "sysemu/device_tree.h" +#include "hw/boards.h"
#define CPU_NONE 0xFFFFFFFF
@@ -61,6 +63,39 @@ static void generic_loader_reset(void *opaque) } }
+/* + * Insert some FDT nodes for the loaded blob. + */ +static void loader_insert_fdt(GenericLoaderState *s, int size, Error **errp) +{ + MachineState *machine = MACHINE(qdev_get_machine()); + void *fdt = machine->fdt; + g_autofree char *node = g_strdup_printf("/chosen/module@%#08lx", s->addr); + uint64_t reg_attr[2] = {cpu_to_be64(s->addr), cpu_to_be64(size)}; + + if (!fdt) { + error_setg(errp, "Cannot modify FDT fields if the machine has none"); + return; + } + + qemu_fdt_add_subnode(fdt, node); + qemu_fdt_setprop(fdt, node, "reg", ®_attr, sizeof(reg_attr)); + + if (s->fdt_compat) { + if (qemu_fdt_setprop_string_array + (fdt, node, "compatible", s->fdt_compat, s->fdt_compat_count) < 0) { + error_setg(errp, "couldn't set %s/compatible", node); + return; + } + } + + if (s->fdt_bootargs) { + if (qemu_fdt_setprop_string(fdt, node, "bootargs", s->fdt_bootargs) < 0) { + error_setg(errp, "couldn't set %s/bootargs", node); + } + } +} + static void generic_loader_realize(DeviceState *dev, Error **errp) { GenericLoaderState *s = GENERIC_LOADER(dev); @@ -171,6 +206,10 @@ static void generic_loader_realize(DeviceState *dev, Error **errp) } else { s->data = cpu_to_le64(s->data); } + + if (s->fdt_compat || s->fdt_bootargs) { + loader_insert_fdt(s, size, errp); + } }
static void generic_loader_unrealize(DeviceState *dev) @@ -186,6 +225,9 @@ static Property generic_loader_props[] = { DEFINE_PROP_UINT32("cpu-num", GenericLoaderState, cpu_num, CPU_NONE), DEFINE_PROP_BOOL("force-raw", GenericLoaderState, force_raw, false), DEFINE_PROP_STRING("file", GenericLoaderState, file), + DEFINE_PROP_ARRAY("fdt-compat", GenericLoaderState, fdt_compat_count, + fdt_compat, qdev_prop_string, char *), + DEFINE_PROP_STRING("fdt-bootargs", GenericLoaderState, fdt_bootargs), DEFINE_PROP_END_OF_LIST(), };