Daniel Henrique Barboza <danielhb...@gmail.com> writes:
> 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' paramenter and, if a valid
> FDT is available, it'll save it in a file 'filename'. In short, this is
> a '-machine dumpdtb' that can be fired on demand via QMP/HMP.
>
> A valid FDT consists of a FDT that was created using libfdt being
> retrieved via 'current_machine->fdt' in device_tree.c. This condition is
> met by most FDT users in QEMU.
>
> 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 <dgilb...@redhat.com>
> Reviewed-by: Alistair Francis <alistair.fran...@wdc.com>
> Signed-off-by: Daniel Henrique Barboza <danielhb...@gmail.com>
> ---
> hmp-commands.hx | 13 +++++++++++++
> include/monitor/hmp.h | 1 +
> include/sysemu/device_tree.h | 1 +
> monitor/hmp-cmds.c | 12 ++++++++++++
> monitor/qmp-cmds.c | 13 +++++++++++++
> qapi/machine.json | 17 +++++++++++++++++
> softmmu/device_tree.c | 18 ++++++++++++++++++
> 7 files changed, 75 insertions(+)
>
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index 182e639d14..2dd737078e 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -1800,3 +1800,16 @@ ERST
> "\n\t\t\t\t\t limit on a specified virtual cpu",
> .cmd = hmp_cancel_vcpu_dirty_limit,
> },
> +
> +SRST
> +``dumpdtb`` *filename*
> + Save the FDT in the 'filename' file to be decoded using dtc.
> + Requires 'libfdt' support.
> +ERST
> + {
> + .name = "dumpdtb",
> + .args_type = "filename:F",
> + .params = "filename",
> + .help = "save the FDT in the 'filename' file to be decoded
> using dtc",
> + .cmd = hmp_dumpdtb,
> + },
> diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h
> index a618eb1e4e..d7f324da59 100644
> --- a/include/monitor/hmp.h
> +++ b/include/monitor/hmp.h
> @@ -134,6 +134,7 @@ void hmp_calc_dirty_rate(Monitor *mon, const QDict
> *qdict);
> void hmp_set_vcpu_dirty_limit(Monitor *mon, const QDict *qdict);
> void hmp_cancel_vcpu_dirty_limit(Monitor *mon, const QDict *qdict);
> void hmp_info_vcpu_dirty_limit(Monitor *mon, const QDict *qdict);
> +void hmp_dumpdtb(Monitor *mon, const QDict *qdict);
> void hmp_human_readable_text_helper(Monitor *mon,
> HumanReadableText *(*qmp_handler)(Error
> **));
> void hmp_info_stats(Monitor *mon, const QDict *qdict);
> diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
> index ef060a9759..bf7684e4ed 100644
> --- 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 qemu_fdt_qmp_dumpdtb(const char *filename, Error **errp);
>
> /**
> * qemu_fdt_setprop_sized_cells_from_array:
> diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
> index c6cd6f91dd..1c7bfd3b9d 100644
> --- a/monitor/hmp-cmds.c
> +++ b/monitor/hmp-cmds.c
> @@ -2472,3 +2472,15 @@ exit:
> exit_no_print:
> error_free(err);
> }
> +
> +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 (local_err) {
> + hmp_handle_error(mon, local_err);
> + }
Make this unconditional, please.
> +}
> diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
> index 7314cd813d..8415aca08c 100644
> --- a/monitor/qmp-cmds.c
> +++ b/monitor/qmp-cmds.c
> @@ -45,6 +45,7 @@
> #include "hw/intc/intc.h"
> #include "hw/rdma/rdma.h"
> #include "monitor/stats.h"
> +#include "sysemu/device_tree.h"
>
> NameInfo *qmp_query_name(Error **errp)
> {
> @@ -596,3 +597,15 @@ bool apply_str_list_filter(const char *string, strList
> *list)
> }
> return false;
> }
> +
> +#ifdef CONFIG_FDT
> +void qmp_dumpdtb(const char *filename, Error **errp)
> +{
> + return qemu_fdt_qmp_dumpdtb(filename, errp);
> +}
> +#else
> +void qmp_dumpdtb(const char *filename, Error **errp)
> +{
> + error_setg(errp, "dumpdtb requires libfdt");
Bad error message, in my opinion: not enough information to be
actionable. But see below.
> +}
> +#endif
Have you considered adding this to softmmu/device_tree.c instead?
> diff --git a/qapi/machine.json b/qapi/machine.json
> index 6afd1936b0..aeb013f3dd 100644
> --- a/qapi/machine.json
> +++ b/qapi/machine.json
> @@ -1664,3 +1664,20 @@
> '*size': 'size',
> '*max-size': 'size',
> '*slots': 'uint64' } }
> +
> +##
> +# @dumpdtb:
> +#
> +# Save the FDT in dtb format. Requires 'libfdt' support.
> +#
> +# @filename: name of the FDT file to be created
> +#
> +# Since: 7.2
> +#
> +# Example:
> +# {"execute": "dumpdtb"}
> +# "arguments": { "filename": "/tmp/fdt.dtb" } }
> +#
> +##
> +{ 'command': 'dumpdtb',
> + 'data': { 'filename': 'str' } }
Why isn't this 'if': 'CONFIG_FDT'?
If it was, you wouldn't need a qmp_dumpdtb() dummy that always fails.
Same for HMP.
> diff --git a/softmmu/device_tree.c b/softmmu/device_tree.c
> index 6ca3fad285..cd487ddd4d 100644
> --- a/softmmu/device_tree.c
> +++ b/softmmu/device_tree.c
> @@ -643,3 +643,21 @@ out:
> g_free(propcells);
> return ret;
> }
> +
> +void qemu_fdt_qmp_dumpdtb(const char *filename, Error **errp)
> +{
> + int size;
> +
> + if (!current_machine->fdt) {
> + error_setg(errp, "Unable to find the machine FDT");
> + return;
> + }
> +
> + size = fdt_totalsize(current_machine->fdt);
> +
> + if (g_file_set_contents(filename, current_machine->fdt, size, NULL)) {
> + return;
> + }
> +
> + error_setg(errp, "Error when saving machine FDT to file %s", filename);
> +}
Unhelpful error reporting. Please try something like
g_autoptr(GError) err = NULL;
if (!g_file_set_contents(filename, current_machine->fdt, size, &err)) {
error_setg(errp, "Error saving FDT to file %s: %s",
filename, err->message);
return;
}
