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-rw-r--r--hw/core/machine.c29
-rw-r--r--hw/i386/pc.c29
-rw-r--r--qemu-options.hx11
3 files changed, 40 insertions, 29 deletions
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 596e758133..d8f458db60 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -760,25 +760,28 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
}
/* compute missing values, prefer sockets over cores over threads */
- maxcpus = maxcpus > 0 ? maxcpus : cpus;
-
- if (cpus == 0) {
+ if (cpus == 0 && maxcpus == 0) {
sockets = sockets > 0 ? sockets : 1;
cores = cores > 0 ? cores : 1;
threads = threads > 0 ? threads : 1;
- cpus = sockets * cores * threads;
+ } else {
maxcpus = maxcpus > 0 ? maxcpus : cpus;
- } else if (sockets == 0) {
- cores = cores > 0 ? cores : 1;
- threads = threads > 0 ? threads : 1;
- sockets = maxcpus / (cores * threads);
- } else if (cores == 0) {
- threads = threads > 0 ? threads : 1;
- cores = maxcpus / (sockets * threads);
- } else if (threads == 0) {
- threads = maxcpus / (sockets * cores);
+
+ if (sockets == 0) {
+ cores = cores > 0 ? cores : 1;
+ threads = threads > 0 ? threads : 1;
+ sockets = maxcpus / (cores * threads);
+ } else if (cores == 0) {
+ threads = threads > 0 ? threads : 1;
+ cores = maxcpus / (sockets * threads);
+ } else if (threads == 0) {
+ threads = maxcpus / (sockets * cores);
+ }
}
+ maxcpus = maxcpus > 0 ? maxcpus : sockets * cores * threads;
+ cpus = cpus > 0 ? cpus : maxcpus;
+
if (sockets * cores * threads < cpus) {
error_setg(errp, "cpu topology: "
"sockets (%u) * cores (%u) * threads (%u) < "
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index e37e84cc7b..f24a1d72ad 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -727,25 +727,28 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
dies = dies > 0 ? dies : 1;
/* compute missing values, prefer sockets over cores over threads */
- maxcpus = maxcpus > 0 ? maxcpus : cpus;
-
- if (cpus == 0) {
+ if (cpus == 0 && maxcpus == 0) {
sockets = sockets > 0 ? sockets : 1;
cores = cores > 0 ? cores : 1;
threads = threads > 0 ? threads : 1;
- cpus = sockets * dies * cores * threads;
+ } else {
maxcpus = maxcpus > 0 ? maxcpus : cpus;
- } else if (sockets == 0) {
- cores = cores > 0 ? cores : 1;
- threads = threads > 0 ? threads : 1;
- sockets = maxcpus / (dies * cores * threads);
- } else if (cores == 0) {
- threads = threads > 0 ? threads : 1;
- cores = maxcpus / (sockets * dies * threads);
- } else if (threads == 0) {
- threads = maxcpus / (sockets * dies * cores);
+
+ if (sockets == 0) {
+ cores = cores > 0 ? cores : 1;
+ threads = threads > 0 ? threads : 1;
+ sockets = maxcpus / (dies * cores * threads);
+ } else if (cores == 0) {
+ threads = threads > 0 ? threads : 1;
+ cores = maxcpus / (sockets * dies * threads);
+ } else if (threads == 0) {
+ threads = maxcpus / (sockets * dies * cores);
+ }
}
+ maxcpus = maxcpus > 0 ? maxcpus : sockets * dies * cores * threads;
+ cpus = cpus > 0 ? cpus : maxcpus;
+
if (sockets * dies * cores * threads < cpus) {
error_setg(errp, "cpu topology: "
"sockets (%u) * dies (%u) * cores (%u) * threads (%u) < "
diff --git a/qemu-options.hx b/qemu-options.hx
index 4a092a092a..2eac830fdb 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -220,9 +220,14 @@ SRST
Simulate a SMP system with '\ ``n``\ ' CPUs initially present on
the machine type board. On boards supporting CPU hotplug, the optional
'\ ``maxcpus``\ ' parameter can be set to enable further CPUs to be
- added at runtime. If omitted the maximum number of CPUs will be
- set to match the initial CPU count. Both parameters are subject to
- an upper limit that is determined by the specific machine type chosen.
+ added at runtime. When both parameters are omitted, the maximum number
+ of CPUs will be calculated from the provided topology members and the
+ initial CPU count will match the maximum number. When only one of them
+ is given then the omitted one will be set to its counterpart's value.
+ Both parameters may be specified, but the maximum number of CPUs must
+ be equal to or greater than the initial CPU count. Both parameters are
+ subject to an upper limit that is determined by the specific machine
+ type chosen.
To control reporting of CPU topology information, the number of sockets,
dies per socket, cores per die, and threads per core can be specified.