* Daniel Henrique Barboza (danielhb...@gmail.com) wrote:
>
>
> On 8/8/22 00:30, David Gibson wrote:
> > On Fri, Aug 05, 2022 at 06:39:42AM -0300, Daniel Henrique Barboza wrote:
> > > 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.
> >
> > On spapr at least, the fdt can change at runtime (due to hotplugs).
> > So we need to think about concurrency between fdt updates and dumping
> > it with this command. I'm assuming it's protected by the BQL, but I'm
> > wondering if we should outright state that somewhere for clarity.
>
> Your assumption is right. It is protected by BQL since it's always executed
> in-band. To not hold BQL we would need to declare an extra flag "allow-oob"
> to execute the command out-of-band.
>
> I'll mention in the commit msg that we're holding BQL. I'll do the same for
> the 'info fdt' commit msg.
Is the update of the FDT also protected that way?
(I guess hotplug commands are also protected by the bql - but is the
hotplug completion?)
Dave
>
> Thanks,
>
>
> Daniel
>
>
> >
> > >
> > > Cc: Dr. David Alan Gilbert <dgilb...@redhat.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..d2554e9701 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:s",
> > > + .params = "[filename] file to save the FDT",
> > > + .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..d23ec85f9d 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) {
> > > + error_report_err(local_err);
> > > + }
> > > +}
> > > 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");
> > > +}
> > > +#endif
> > > 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' } }
> > > 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);
> > > +}
> >
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
