qmp/hmp, device_tree.c: introduce dumpdtb

To save the FDT blob we have the '-machine dumpdtb=<file>' property.
With this property set, the machine saves the FDT in <file> and exit.
The created file can then be converted to plain text dts format using
'dtc'.

There's nothing particularly sophisticated into saving the FDT that
can't be done with the machine at any state, as long as the machine has
a valid FDT to be saved.

The 'dumpdtb' command receives a 'filename' parameter and, if the FDT is
available via current_machine->fdt, save it in dtb format to 'filename'.
In short, this is a '-machine dumpdtb' that can be fired on demand via
QMP/HMP.

This command will always be executed in-band (i.e. holding BQL),
avoiding potential race conditions with machines that might change the
FDT during runtime (e.g. PowerPC 'pseries' machine).

Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Alistair Francis <alistair.francis@wdc.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20220926173855.1159396-2-danielhb413@gmail.com>

diff --git a/hmp-commands.hx b/hmp-commands.hx
index 8ab8000acd9e2faa826ac6cf9551fc07500a6952..12b6d4e2dcacdacc6eee523cb45de9728698b993 100644 (file)
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1800,3 +1800,18 @@ ERST
         .sub_table  = hmp_info_cmds,
         .flags      = "p",
     },
+
+#if defined(CONFIG_FDT)
+    {
+        .name       = "dumpdtb",
+        .args_type  = "filename:F",
+        .params     = "filename",
+        .help       = "dump the FDT in dtb format to 'filename'",
+        .cmd        = hmp_dumpdtb,
+    },
+
+SRST
+``dumpdtb`` *filename*
+  Dump the FDT in dtb format to *filename*.
+ERST
+#endif

diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
index ef060a97590e13640afa58dbfb855014978ae0d0..e7c5441f564544475f143456588577469908a343 100644 (file)
--- a/include/sysemu/device_tree.h
+++ b/include/sysemu/device_tree.h
@@ -136,6 +136,7 @@ int qemu_fdt_add_path(void *fdt, const char *path);
     } while (0)
 
 void qemu_fdt_dumpdtb(void *fdt, int size);
+void hmp_dumpdtb(Monitor *mon, const QDict *qdict);
 
 /**
  * qemu_fdt_setprop_sized_cells_from_array:

diff --git a/monitor/misc.c b/monitor/misc.c
index 6436a8786b442223254c27da9cbb0913729bea79..205487e2b9ed6f5841f5f0faa796a1b16a6d9271 100644 (file)
--- a/monitor/misc.c
+++ b/monitor/misc.c
@@ -49,6 +49,7 @@
 #include "sysemu/blockdev.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/tpm.h"
+#include "sysemu/device_tree.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qmp/qerror.h"
 #include "qapi/qmp/qstring.h"

diff --git a/qapi/machine.json b/qapi/machine.json
index abb2f48808e52c76763729e6ee47833c41e61f07..b9228a5e46169e5d29abd08244d1022abdca955e 100644 (file)
--- a/qapi/machine.json
+++ b/qapi/machine.json
@@ -1664,3 +1664,21 @@
      '*size': 'size',
      '*max-size': 'size',
      '*slots': 'uint64' } }
+
+##
+# @dumpdtb:
+#
+# Save the FDT in dtb format.
+#
+# @filename: name of the dtb file to be created
+#
+# Since: 7.2
+#
+# Example:
+#   {"execute": "dumpdtb"}
+#    "arguments": { "filename": "fdt.dtb" } }
+#
+##
+{ 'command': 'dumpdtb',
+  'data': { 'filename': 'str' },
+  'if': 'CONFIG_FDT' }

diff --git a/softmmu/device_tree.c b/softmmu/device_tree.c
index 6ca3fad28556af087dc7707c5a95428a82b6c970..ce74f3d48d7c7d6ef62cb8091c4fc6ffe0ece3b6 100644 (file)
--- a/softmmu/device_tree.c
+++ b/softmmu/device_tree.c
@@ -26,6 +26,9 @@
 #include "hw/loader.h"
 #include "hw/boards.h"
 #include "qemu/config-file.h"
+#include "qapi/qapi-commands-machine.h"
+#include "qapi/qmp/qdict.h"
+#include "monitor/hmp.h"
 
 #include <libfdt.h>
 
@@ -643,3 +646,37 @@ out:
     g_free(propcells);
     return ret;
 }
+
+void qmp_dumpdtb(const char *filename, Error **errp)
+{
+    g_autoptr(GError) err = NULL;
+    uint32_t size;
+
+    if (!current_machine->fdt) {
+        error_setg(errp, "This machine doesn't have a FDT");
+        return;
+    }
+
+    size = fdt_totalsize(current_machine->fdt);
+
+    g_assert(size > 0);
+
+    if (!g_file_set_contents(filename, current_machine->fdt, size, &err)) {
+        error_setg(errp, "Error saving FDT to file %s: %s",
+                   filename, err->message);
+    }
+}
+
+void hmp_dumpdtb(Monitor *mon, const QDict *qdict)
+{
+    const char *filename = qdict_get_str(qdict, "filename");
+    Error *local_err = NULL;
+
+    qmp_dumpdtb(filename, &local_err);
+
+    if (hmp_handle_error(mon, local_err)) {
+        return;
+    }
+
+    info_report("dtb dumped to %s", filename);
+}