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Tsirkin" , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= Cc: qemu-devel@nongnu.org, Zhao Liu Subject: [PATCH] i386/apic: Add hint on boot failure because of disabling x2APIC Date: Thu, 6 Jun 2024 22:08:58 +0800 Message-Id: <20240606140858.2157106-1-zhao1.liu@intel.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Received-SPF: pass client-ip=192.198.163.19; envelope-from=zhao1.liu@intel.com; helo=mgamail.intel.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, 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-bounces+qemu-devel=archiver.kernel.org@nongnu.org Currently, the Q35 supports up to 4096 vCPUs (since v9.0), but for TCG cases, if x2APIC is not actively enabled to boot more than 255 vCPUs ( e.g., qemu-system-i386 -M pc-q35-9.0 -smp 666), the following error is reported: Unexpected error in apic_common_set_id() at ../hw/intc/apic_common.c:449: qemu-system-i386: APIC ID 255 requires x2APIC feature in CPU Aborted (core dumped) This error can be resolved by setting x2apic=on in -cpu. In order to better help users deal with this scenario, add the error hint to instruct users on how to enable the x2apic feature. Then, the error report becomes the following: Unexpected error in apic_common_set_id() at ../hw/intc/apic_common.c:448: qemu-system-i386: APIC ID 255 requires x2APIC feature in CPU Try x2apic=on in -cpu. Aborted (core dumped) Note since @errp is &error_abort, error_append_hint() can't be applied on @errp. And in order to separate the exact error message from the (perhaps effectively) hint, adding a hint via error_append_hint() is also necessary. Therefore, introduce @local_error in apic_common_set_id() to handle both the error message and the error hint. Suggested-by: Philippe Mathieu-Daudé Signed-off-by: Zhao Liu Reviewed-by: Philippe Mathieu-Daudé --- hw/intc/apic_common.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c index d8fc1e2815fe..c13cdd79943d 100644 --- a/hw/intc/apic_common.c +++ b/hw/intc/apic_common.c @@ -433,6 +433,7 @@ static void apic_common_set_id(Object *obj, Visitor *v, const char *name, APICCommonState *s = APIC_COMMON(obj); DeviceState *dev = DEVICE(obj); uint32_t value; + Error *local_err = NULL; if (dev->realized) { qdev_prop_set_after_realize(dev, name, errp); @@ -444,7 +445,11 @@ static void apic_common_set_id(Object *obj, Visitor *v, const char *name, } if (value >= 255 && !cpu_has_x2apic_feature(&s->cpu->env)) { - error_setg(errp, "APIC ID %d requires x2APIC feature in CPU", value); + error_setg(&local_err, + "APIC ID %d requires x2APIC feature in CPU", + value); + error_append_hint(&local_err, "Try x2apic=on in -cpu.\n"); + error_propagate(errp, local_err); return; }