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[82.30.61.225]) by smtp.gmail.com with ESMTPSA id q18-20020adff952000000b00222ed7ea203sm7821569wrr.100.2022.08.15.11.31.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Aug 2022 11:31:44 -0700 (PDT) Date: Mon, 15 Aug 2022 19:31:42 +0100 From: "Dr. David Alan Gilbert" To: Daniel Henrique Barboza Cc: David Gibson , qemu-devel@nongnu.org, alistair.francis@wdc.com Subject: Re: [PATCH for-7.2 v2 14/20] qmp/hmp, device_tree.c: introduce dumpdtb Message-ID: References: <20220805093948.82561-1-danielhb413@gmail.com> <20220805093948.82561-15-danielhb413@gmail.com> <7a5a55f5-2e60-e34b-f84a-85ae4c122f7f@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7a5a55f5-2e60-e34b-f84a-85ae4c122f7f@gmail.com> User-Agent: Mutt/2.2.6 (2022-06-05) Received-SPF: pass client-ip=170.10.129.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Daniel Henrique Barboza (danielhb413@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=' property. > > > With this property set, the machine saves the FDT in 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 > > > Signed-off-by: Daniel Henrique Barboza > > > --- > > > 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 / dgilbert@redhat.com / Manchester, UK