<div dir="ltr"><div>hi ,</div><div><br></div><div>I used libvirt upstream code version v7.3.0-135-gc6989ed929 and applied the patch. It failed to compile the code with below errors,  can you please check them?</div><div><br></div>../src/conf/domain_conf.c: In function ‘virDomainIOMMUDefCheckABIStability’:<br>../src/conf/domain_conf.c:22064:12: error: ‘virDomainIOMMUDef’ {aka ‘struct _virDomainIOMMUDef’} has no member named ‘mem’<br>22064 |     if (src->mem.max_ram_below_4g != dst->mem.max_ram_below_4g) {<br>      |            ^~<br>../src/conf/domain_conf.c:22064:41: error: ‘virDomainIOMMUDef’ {aka ‘struct _virDomainIOMMUDef’} has no member named ‘mem’<br>22064 |     if (src->mem.max_ram_below_4g != dst->mem.max_ram_below_4g) {<br>      |                                         ^~<br>In file included from ../src/conf/domain_conf.c:31:<br>../src/conf/domain_conf.c:22068:27: error: ‘virDomainIOMMUDef’ {aka ‘struct _virDomainIOMMUDef’} has no member named ‘mem’<br>22068 |                        dst->mem.max_ram_below_4g,<br>      |                           ^~<br>../src/util/virerror.h:177:50: note: in definition of macro ‘virReportError’<br>  177 |                          __FUNCTION__, __LINE__, __VA_ARGS__)<br>      |                                                  ^~~~~~~~~~~<br>../src/conf/domain_conf.c:22069:27: error: ‘virDomainIOMMUDef’ {aka ‘struct _virDomainIOMMUDef’} has no member named ‘mem’<br>22069 |                        src->mem.max_ram_below_4g);<br>      |                           ^~<br>../src/util/virerror.h:177:50: note: in definition of macro ‘virReportError’<br>  177 |                          __FUNCTION__, __LINE__, __VA_ARGS__)<br>      |                                                  ^~~~~~~~~~~<br><div><br></div><div>Thanks,</div><div>Jing Qi</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, May 6, 2021 at 4:29 PM Zhiyong Ye <<a href="mailto:yezhiyong@bytedance.com">yezhiyong@bytedance.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">The 'below4g' attribute added in 'memory' element can be used to specify<br>
the low memory area, which allows to get a larger PCI I/O window below<br>
4G when reduce it to a smaller value, and when raise value allows legacy<br>
non-PAE guests to have as much memory as possible in the 32bit address<br>
space below 4G. It does not share the 'unit' parameter with the actual<br>
memory size and its unit defaults to "KiB".<br>
<br>
Signed-off-by: Zhiyong Ye <<a href="mailto:yezhiyong@bytedance.com" target="_blank">yezhiyong@bytedance.com</a>><br>
Signed-off-by: zhenwei pi <<a href="mailto:pizhenwei@bytedance.com" target="_blank">pizhenwei@bytedance.com</a>><br>
Signed-off-by: zhangruien <<a href="mailto:zhangruien@bytedance.com" target="_blank">zhangruien@bytedance.com</a>><br>
---<br>
 docs/formatdomain.rst                       | 10 ++++++--<br>
 docs/schemas/domaincommon.rng               |  5 ++++<br>
 src/conf/domain_conf.c                      | 15 ++++++++++++<br>
 src/conf/domain_conf.h                      |  3 +++<br>
 src/conf/domain_validate.c                  | 13 ++++++++++<br>
 src/qemu/qemu_command.c                     |  4 ++++<br>
 tests/qemuxml2argvdata/memory-below4g.args  | 29 ++++++++++++++++++++++<br>
 tests/qemuxml2argvdata/memory-below4g.xml   | 26 ++++++++++++++++++++<br>
 tests/qemuxml2argvtest.c                    |  1 +<br>
 tests/qemuxml2xmloutdata/memory-below4g.xml | 37 +++++++++++++++++++++++++++++<br>
 tests/qemuxml2xmltest.c                     |  1 +<br>
 11 files changed, 142 insertions(+), 2 deletions(-)<br>
 create mode 100644 tests/qemuxml2argvdata/memory-below4g.args<br>
 create mode 100644 tests/qemuxml2argvdata/memory-below4g.xml<br>
 create mode 100644 tests/qemuxml2xmloutdata/memory-below4g.xml<br>
<br>
diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst<br>
index fa5c14febc..a71a716f5b 100644<br>
--- a/docs/formatdomain.rst<br>
+++ b/docs/formatdomain.rst<br>
@@ -940,8 +940,14 @@ Memory Allocation<br>
    `NUMA <#elementsCPU>`__ is configured for the guest the ``memory`` element<br>
    can be omitted. In the case of crash, optional attribute ``dumpCore`` can be<br>
    used to control whether the guest memory should be included in the generated<br>
-   coredump or not (values "on", "off"). ``unit`` :since:`since 0.9.11` ,<br>
-   ``dumpCore`` :since:`since 0.10.2 (QEMU only)`<br>
+   coredump or not (values "on", "off"). Besides, the optional ``below4g``<br>
+   attribute can be used to specify the low memory area, which allows to get a<br>
+   larger PCI I/O window below 4G when reduce it to a smaller value, and when<br>
+   raise value allows legacy non-PAE guests to have as much memory as possible<br>
+   in the 32bit address space below 4G. It does not share the ``unit`` parameter<br>
+   with the actual memory size and its unit defaults to "KiB". ``unit`` :<br>
+   since:`since 0.9.11` , ``dumpCore`` : since:`since 0.10.2 (QEMU only)`,<br>
+   ``below4g`` :since:`since 7.3.0 (QEMU only)`.<br>
 ``maxMemory``<br>
    The run time maximum memory allocation of the guest. The initial memory<br>
    specified by either the ``<memory>`` element or the NUMA cell size<br>
diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng<br>
index a2e5c50c1d..8f2ac1ad33 100644<br>
--- a/docs/schemas/domaincommon.rng<br>
+++ b/docs/schemas/domaincommon.rng<br>
@@ -643,6 +643,11 @@<br>
               <ref name="virOnOff"/><br>
             </attribute><br>
           </optional><br>
+          <optional><br>
+            <attribute name="below4g"><br>
+              <ref name="unsignedLong"/><br>
+            </attribute><br>
+          </optional><br>
         </element><br>
       </optional><br>
       <optional><br>
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c<br>
index 77105e6a07..8573967c4b 100644<br>
--- a/src/conf/domain_conf.c<br>
+++ b/src/conf/domain_conf.c<br>
@@ -19239,6 +19239,10 @@ virDomainDefParseMemory(virDomainDef *def,<br>
                              &def->mem.max_memory, false, false) < 0)<br>
         goto error;<br>
<br>
+    if (virDomainParseMemory("./memory[1]/@below4g", NULL, ctxt,<br>
+                             &def->mem.max_ram_below_4g, false, true) < 0)<br>
+        goto error;<br>
+<br>
     if (virXPathUInt("string(./maxMemory[1]/@slots)", ctxt, &def->mem.memory_slots) == -2) {<br>
         virReportError(VIR_ERR_XML_ERROR, "%s",<br>
                        _("Failed to parse memory slot count"));<br>
@@ -22374,6 +22378,15 @@ virDomainIOMMUDefCheckABIStability(virDomainIOMMUDef *src,<br>
         return false;<br>
     }<br>
<br>
+    if (src->mem.max_ram_below_4g != dst->mem.max_ram_below_4g) {<br>
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,<br>
+                       _("Target domain maximum memory below the 4GiB boundary "<br>
+                         "'%llu' doesn't match source '%llu'"),<br>
+                       dst->mem.max_ram_below_4g,<br>
+                       src->mem.max_ram_below_4g);<br>
+        return false;<br>
+    }<br>
+<br>
     return true;<br>
 }<br>
<br>
@@ -28297,6 +28310,8 @@ virDomainDefFormatInternalSetRootName(virDomainDef *def,<br>
     if (def->mem.dump_core)<br>
         virBufferAsprintf(buf, " dumpCore='%s'",<br>
                           virTristateSwitchTypeToString(def->mem.dump_core));<br>
+    if (def->mem.max_ram_below_4g > 0)<br>
+        virBufferAsprintf(buf, " below4g='%llu'", def->mem.max_ram_below_4g);<br>
     virBufferAsprintf(buf, " unit='KiB'>%llu</memory>\n",<br>
                       virDomainDefGetMemoryTotal(def));<br>
<br>
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h<br>
index 95d0516279..d0418eb9ed 100644<br>
--- a/src/conf/domain_conf.h<br>
+++ b/src/conf/domain_conf.h<br>
@@ -2597,6 +2597,9 @@ struct _virDomainMemtune {<br>
     unsigned long long max_memory; /* in kibibytes */<br>
     unsigned int memory_slots; /* maximum count of RAM memory slots */<br>
<br>
+    /* maximum memory below the 4GiB boundary (32bit boundary) */<br>
+    unsigned long long max_ram_below_4g; /* in kibibytes */<br>
+<br>
     bool nosharepages;<br>
     bool locked;<br>
     int dump_core; /* enum virTristateSwitch */<br>
diff --git a/src/conf/domain_validate.c b/src/conf/domain_validate.c<br>
index 686b9e8d16..afa9e2e821 100644<br>
--- a/src/conf/domain_validate.c<br>
+++ b/src/conf/domain_validate.c<br>
@@ -1384,6 +1384,19 @@ virDomainDefMemtuneValidate(const virDomainDef *def)<br>
         }<br>
     }<br>
<br>
+    if (mem->max_ram_below_4g &&<br>
+        mem->max_ram_below_4g < 1024) {<br>
+        virReportError(VIR_ERR_XML_DETAIL, "%s",<br>
+                       _("maximum memory size below the 4GiB boundary must be "<br>
+                         "greater than or equal to 1MiB"));<br>
+        return -1;<br>
+    } else if (mem->max_ram_below_4g > 4 * 1024 * 1024) {<br>
+        virReportError(VIR_ERR_XML_DETAIL, "%s",<br>
+                       _("maximum memory size below the 4GiB boundary must be "<br>
+                         "less than or equal to 4GiB"));<br>
+        return -1;<br>
+    }<br>
+<br>
     return 0;<br>
 }<br>
<br>
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c<br>
index ca2265cc90..97c65a6bf1 100644<br>
--- a/src/qemu/qemu_command.c<br>
+++ b/src/qemu/qemu_command.c<br>
@@ -6849,6 +6849,10 @@ qemuBuildMachineCommandLine(virCommand *cmd,<br>
                           cfg->dumpGuestCore ? "on" : "off");<br>
     }<br>
<br>
+    if (def->mem.max_ram_below_4g > 0)<br>
+        virBufferAsprintf(&buf, ",max-ram-below-4g=%llu",<br>
+                          def->mem.max_ram_below_4g * 1024);<br>
+<br>
     if (def->mem.nosharepages)<br>
         virBufferAddLit(&buf, ",mem-merge=off");<br>
<br>
diff --git a/tests/qemuxml2argvdata/memory-below4g.args b/tests/qemuxml2argvdata/memory-below4g.args<br>
new file mode 100644<br>
index 0000000000..f55386a2a2<br>
--- /dev/null<br>
+++ b/tests/qemuxml2argvdata/memory-below4g.args<br>
@@ -0,0 +1,29 @@<br>
+LC_ALL=C \<br>
+PATH=/bin \<br>
+HOME=/tmp/lib/domain--1-QEMUGuest1 \<br>
+USER=test \<br>
+LOGNAME=test \<br>
+XDG_DATA_HOME=/tmp/lib/domain--1-QEMUGuest1/.local/share \<br>
+XDG_CACHE_HOME=/tmp/lib/domain--1-QEMUGuest1/.cache \<br>
+XDG_CONFIG_HOME=/tmp/lib/domain--1-QEMUGuest1/.config \<br>
+QEMU_AUDIO_DRV=none \<br>
+/usr/bin/qemu-system-i386 \<br>
+-name QEMUGuest1 \<br>
+-S \<br>
+-machine pc,accel=tcg,usb=off,dump-guest-core=off,max-ram-below-4g=112197632 \<br>
+-m 214 \<br>
+-realtime mlock=off \<br>
+-smp 1,sockets=1,cores=1,threads=1 \<br>
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \<br>
+-display none \<br>
+-no-user-config \<br>
+-nodefaults \<br>
+-chardev socket,id=charmonitor,path=/tmp/lib/domain--1-QEMUGuest1/monitor.sock,server=on,wait=off \<br>
+-mon chardev=charmonitor,id=monitor,mode=control \<br>
+-rtc base=utc \<br>
+-no-shutdown \<br>
+-no-acpi \<br>
+-usb \<br>
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-ide0-0-0 \<br>
+-device ide-hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1 \<br>
+-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3<br>
diff --git a/tests/qemuxml2argvdata/memory-below4g.xml b/tests/qemuxml2argvdata/memory-below4g.xml<br>
new file mode 100644<br>
index 0000000000..a843ef72a2<br>
--- /dev/null<br>
+++ b/tests/qemuxml2argvdata/memory-below4g.xml<br>
@@ -0,0 +1,26 @@<br>
+<domain type='qemu'><br>
+  <name>QEMUGuest1</name><br>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid><br>
+  <memory below4g='109568' unit='MiB'>214</memory><br>
+  <currentMemory unit='KiB'>219136</currentMemory><br>
+  <vcpu placement='static'>1</vcpu><br>
+  <os><br>
+    <type arch='i686' machine='pc'>hvm</type><br>
+    <boot dev='hd'/><br>
+  </os><br>
+  <clock offset='utc'/><br>
+  <on_poweroff>destroy</on_poweroff><br>
+  <on_reboot>restart</on_reboot><br>
+  <on_crash>destroy</on_crash><br>
+  <devices><br>
+    <emulator>/usr/bin/qemu-system-i386</emulator><br>
+    <disk type='block' device='disk'><br>
+      <source dev='/dev/HostVG/QEMUGuest1'/><br>
+      <target dev='hda' bus='ide'/><br>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/><br>
+    </disk><br>
+    <controller type='usb' index='0'/><br>
+    <controller type='ide' index='0'/><br>
+    <memballoon model='virtio'/><br>
+  </devices><br>
+</domain><br>
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c<br>
index a9dafe226e..131ebde9e4 100644<br>
--- a/tests/qemuxml2argvtest.c<br>
+++ b/tests/qemuxml2argvtest.c<br>
@@ -1055,6 +1055,7 @@ mymain(void)<br>
     driver.config->dumpGuestCore = true;<br>
     DO_TEST("machine-core-off", NONE);<br>
     driver.config->dumpGuestCore = false;<br>
+    DO_TEST("memory-below4g", NONE);<br>
     DO_TEST("machine-smm-opt",<br>
             QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,<br>
             QEMU_CAPS_DEVICE_PCI_BRIDGE,<br>
diff --git a/tests/qemuxml2xmloutdata/memory-below4g.xml b/tests/qemuxml2xmloutdata/memory-below4g.xml<br>
new file mode 100644<br>
index 0000000000..44f58fc93b<br>
--- /dev/null<br>
+++ b/tests/qemuxml2xmloutdata/memory-below4g.xml<br>
@@ -0,0 +1,37 @@<br>
+<domain type='qemu'><br>
+  <name>QEMUGuest1</name><br>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid><br>
+  <memory below4g='109568' unit='KiB'>219136</memory><br>
+  <currentMemory unit='KiB'>219136</currentMemory><br>
+  <vcpu placement='static'>1</vcpu><br>
+  <os><br>
+    <type arch='i686' machine='pc'>hvm</type><br>
+    <boot dev='hd'/><br>
+  </os><br>
+  <clock offset='utc'/><br>
+  <on_poweroff>destroy</on_poweroff><br>
+  <on_reboot>restart</on_reboot><br>
+  <on_crash>destroy</on_crash><br>
+  <devices><br>
+    <emulator>/usr/bin/qemu-system-i386</emulator><br>
+    <disk type='block' device='disk'><br>
+      <driver name='qemu' type='raw'/><br>
+      <source dev='/dev/HostVG/QEMUGuest1'/><br>
+      <target dev='hda' bus='ide'/><br>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/><br>
+    </disk><br>
+    <controller type='usb' index='0'><br>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/><br>
+    </controller><br>
+    <controller type='ide' index='0'><br>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/><br>
+    </controller><br>
+    <controller type='pci' index='0' model='pci-root'/><br>
+    <input type='mouse' bus='ps2'/><br>
+    <input type='keyboard' bus='ps2'/><br>
+    <audio id='1' type='none'/><br>
+    <memballoon model='virtio'><br>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/><br>
+    </memballoon><br>
+  </devices><br>
+</domain><br>
diff --git a/tests/qemuxml2xmltest.c b/tests/qemuxml2xmltest.c<br>
index 7af6f90aee..7a139489c3 100644<br>
--- a/tests/qemuxml2xmltest.c<br>
+++ b/tests/qemuxml2xmltest.c<br>
@@ -220,6 +220,7 @@ mymain(void)<br>
     DO_TEST_CAPS_LATEST("genid-auto");<br>
     DO_TEST("machine-core-on", NONE);<br>
     DO_TEST("machine-core-off", NONE);<br>
+    DO_TEST("memory-below4g", NONE);<br>
     DO_TEST("machine-loadparm-multiple-disks-nets-s390", NONE);<br>
     DO_TEST("default-kvm-host-arch", NONE);<br>
     DO_TEST("default-qemu-host-arch", NONE);<br>
-- <br>
2.11.0<br>
<br>
</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr">Thanks & Regards,<br>Jing,Qi<br></div></div>