Hi Prasad, On Mon, Mar 04, 2024 at 11:23:58AM +0530, Prasad Pandit wrote:
Date: Mon, 4 Mar 2024 11:23:58 +0530 From: Prasad Pandit <ppandit@redhat.com> Subject: Re: [PATCH] hw/core/machine-smp: Remove deprecated "parameter=0" SMP configurations
On Mon, 4 Mar 2024 at 10:02, Zhao Liu <zhao1.liu@linux.intel.com> wrote:
diff --git a/hw/core/machine-smp.c b/hw/core/machine-smp.c index 25019c91ee36..96533886b14e 100644 --- a/hw/core/machine-smp.c +++ b/hw/core/machine-smp.c @@ -105,8 +105,9 @@ void machine_parse_smp_config(MachineState *ms, (config->has_cores && config->cores == 0) || (config->has_threads && config->threads == 0) || (config->has_maxcpus && config->maxcpus == 0)) { - warn_report("Deprecated CPU topology (considered invalid): " - "CPU topology parameters must be greater than zero"); + error_setg(errp, "Invalid CPU topology: " + "CPU topology parameters must be greater than zero"); + return; }
unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
This indicates the default maxcpus is initialized as 0 if user doesn't specifies it. For this case - no user configuration - maxcpus will be re-calculated as: maxcpus = maxcpus > 0 ? maxcpus : drawers * books * sockets * dies * clusters * cores * threads; (*)
... if (config->has_maxcpus && config->maxcpus == 0)
This check only wants to identify the case that user sets the 0.
* The check (has_maxcpus && maxcpus == 0) seems to be repeating above, maybe we could check if (maxcpus == 0) error_setg().
If the default maxcpus is initialized as 0, then (maxcpus == 0) will fail if user doesn't set maxcpus. However, we could initialize maxcpus as other default value, e.g., maxcpus = config->has_maxcpus ? config->maxcpus : 1. But it is still necessary to distinguish whether maxcpus is user-set or auto-initialized. If it is user-set, -smp should fail is there's invalid maxcpus/invalid topology. Otherwise, if it is auto-initialized, its value should be adjusted based on other topology components as the above calculation in (*).
And same for other topology parameters?
Other parameters also have the similar needs to distinguish if they're set by user. So the check needs to also cover has_* fields.
* Also a check to ensure cpus <= maxcpus is required I think.
Yes, the valid topology needs this. This code block already covers this case ;-): if (maxcpus < cpus) { g_autofree char *topo_msg = cpu_hierarchy_to_string(ms); error_setg(errp, "Invalid CPU topology: " "maxcpus must be equal to or greater than smp: " "%s == maxcpus (%u) < smp_cpus (%u)", topo_msg, maxcpus, cpus); return; } Thanks, Zhao