On Tue, Aug 16, 2022 at 02:34:28PM -0300, Daniel Henrique Barboza wrote: > 'info fdt' is only able to print full nodes so far. It would be good to > be able to also print single properties, since ometimes we just want > to verify a single value from the FDT. > > libfdt does not have support to find a property given its full path, but > it does have a way to return a fdt_property given a prop name and its > subnode. > > Add a new optional 'propname' parameter to x-query-fdt to specify the > property of a given node. If it's present, we'll proceed to find the > node as usual but, instead of printing the node, we'll attempt to find > the property and print it standalone. > > After this change, if an user wants to print just the value of 'cpu' inside > /cpu/cpu-map(...) from an ARM FDT, we can do it: > > (qemu) info fdt /cpus/cpu-map/socket0/cluster0/core0 cpu > /cpus/cpu-map/socket0/cluster0/core0/cpu = <0x8001> > > Or the 'ibm,my-dma-window' from the v-scsi device inside the pSeries > FDT: > > (qemu) info fdt /vdevice/v-scsi@71000003 ibm,my-dma-window > /vdevice/v-scsi@71000003/ibm,my-dma-window = <0x71000003 0x0 0x0 0x0 > 0x10000000>
nit: dts property definitions also include a terminating ';'
prop = "foobar";
> Cc: Dr. David Alan Gilbert <dgilb...@redhat.com>
> Acked-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> Signed-off-by: Daniel Henrique Barboza <danielhb...@gmail.com>
> ---
> hmp-commands-info.hx | 9 +++++----
> include/sysemu/device_tree.h | 2 ++
> monitor/hmp-cmds.c | 5 ++++-
> monitor/qmp-cmds.c | 8 +++++---
> qapi/machine.json | 4 +++-
> softmmu/device_tree.c | 29 ++++++++++++++++++++++++-----
> 6 files changed, 43 insertions(+), 14 deletions(-)
>
> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
> index 743b48865d..17d6ee4d30 100644
> --- a/hmp-commands-info.hx
> +++ b/hmp-commands-info.hx
> @@ -924,13 +924,14 @@ ERST
>
> {
> .name = "fdt",
> - .args_type = "nodepath:s",
> - .params = "nodepath",
> - .help = "show firmware device tree node given its path",
> + .args_type = "nodepath:s,propname:s?",
> + .params = "nodepath [propname]",
> + .help = "show firmware device tree node or property given its
> path",
> .cmd = hmp_info_fdt,
> },
>
> SRST
> ``info fdt``
> - Show a firmware device tree node given its path. Requires libfdt.
> + Show a firmware device tree node or property given its path.
> + Requires libfdt.
> ERST
> diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
> index 057d13e397..551a02dee2 100644
> --- a/include/sysemu/device_tree.h
> +++ b/include/sysemu/device_tree.h
> @@ -140,6 +140,8 @@ int qemu_fdt_add_path(void *fdt, const char *path);
> void qemu_fdt_dumpdtb(void *fdt, int size);
> void qemu_fdt_qmp_dumpdtb(const char *filename, Error **errp);
> HumanReadableText *qemu_fdt_qmp_query_fdt(const char *nodepath,
> + bool has_propname,
> + const char *propname,
> Error **errp);
>
> /**
> diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
> index accde90380..df8493adc5 100644
> --- a/monitor/hmp-cmds.c
> +++ b/monitor/hmp-cmds.c
> @@ -2488,8 +2488,11 @@ void hmp_dumpdtb(Monitor *mon, const QDict *qdict)
> void hmp_info_fdt(Monitor *mon, const QDict *qdict)
> {
> const char *nodepath = qdict_get_str(qdict, "nodepath");
> + const char *propname = qdict_get_try_str(qdict, "propname");
> Error *err = NULL;
> - g_autoptr(HumanReadableText) info = qmp_x_query_fdt(nodepath, &err);
> + g_autoptr(HumanReadableText) info = NULL;
> +
> + info = qmp_x_query_fdt(nodepath, propname != NULL, propname, &err);
>
> if (hmp_handle_error(mon, err)) {
> return;
> diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
> index db2c6aa7da..ca2a96cdf7 100644
> --- a/monitor/qmp-cmds.c
> +++ b/monitor/qmp-cmds.c
> @@ -604,9 +604,10 @@ void qmp_dumpdtb(const char *filename, Error **errp)
> return qemu_fdt_qmp_dumpdtb(filename, errp);
> }
>
> -HumanReadableText *qmp_x_query_fdt(const char *nodepath, Error **errp)
> +HumanReadableText *qmp_x_query_fdt(const char *nodepath, bool has_propname,
> + const char *propname, Error **errp)
> {
> - return qemu_fdt_qmp_query_fdt(nodepath, errp);
> + return qemu_fdt_qmp_query_fdt(nodepath, has_propname, propname, errp);
> }
> #else
> void qmp_dumpdtb(const char *filename, Error **errp)
> @@ -614,7 +615,8 @@ void qmp_dumpdtb(const char *filename, Error **errp)
> error_setg(errp, "dumpdtb requires libfdt");
> }
>
> -HumanReadableText *qmp_x_query_fdt(const char *nodepath, Error **errp)
> +HumanReadableText *qmp_x_query_fdt(const char *nodepath, bool has_propname,
> + const char *propname, Error **errp)
> {
> error_setg(errp, "this command requires libfdt");
>
> diff --git a/qapi/machine.json b/qapi/machine.json
> index 96cff541ca..c15ce60f46 100644
> --- a/qapi/machine.json
> +++ b/qapi/machine.json
> @@ -1688,6 +1688,7 @@
> # Query for FDT element (node or property). Requires 'libfdt'.
> #
> # @nodepath: the path of the FDT node to be retrieved
> +# @propname: name of the property inside the node
> #
> # Features:
> # @unstable: This command is meant for debugging.
> @@ -1697,6 +1698,7 @@
> # Since: 7.2
> ##
> { 'command': 'x-query-fdt',
> - 'data': { 'nodepath': 'str' },
> + 'data': { 'nodepath': 'str',
> + '*propname': 'str' },
> 'returns': 'HumanReadableText',
> 'features': [ 'unstable' ] }
> diff --git a/softmmu/device_tree.c b/softmmu/device_tree.c
> index 9e681739bd..523c9b8d4d 100644
> --- a/softmmu/device_tree.c
> +++ b/softmmu/device_tree.c
> @@ -823,23 +823,42 @@ static void fdt_format_node(GString *buf, int node, int
> depth,
> g_string_append_printf(buf, "%*s}\n", padding, "");
> }
>
> -HumanReadableText *qemu_fdt_qmp_query_fdt(const char *nodepath, Error **errp)
> +HumanReadableText *qemu_fdt_qmp_query_fdt(const char *nodepath,
> + bool has_propname,
> + const char *propname,
> + Error **errp)
> {
> g_autoptr(GString) buf = g_string_new("");
> - int node;
> + const struct fdt_property *prop = NULL;
> + void *fdt = current_machine->fdt;
> + int node, prop_size;
>
> - if (!current_machine->fdt) {
> + if (!fdt) {
> error_setg(errp, "Unable to find the machine FDT");
> return NULL;
> }
>
> - node = fdt_path_offset(current_machine->fdt, nodepath);
> + node = fdt_path_offset(fdt, nodepath);
> if (node < 0) {
> error_setg(errp, "node '%s' not found in FDT", nodepath);
> return NULL;
> }
>
> - fdt_format_node(buf, node, 0, nodepath);
> + if (!has_propname) {
> + fdt_format_node(buf, node, 0, nodepath);
> + } else {
> + g_autofree char *proppath = g_strdup_printf("%s/%s", nodepath,
> + propname);
> +
> + prop = fdt_get_property(fdt, node, propname, &prop_size);
> + if (!prop) {
> + error_setg(errp, "property '%s' not found in node '%s' in FDT",
> + propname, nodepath);
> + return NULL;
> + }
> +
> + fdt_format_property(buf, proppath, prop->data, prop_size, 0);
> + }
>
> return human_readable_text_from_str(buf);
> }
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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