Re: [PATCH v10 11/14] machine: Make smp_parse generic enough for all arches

["wangyanan (Y)" <wangyanan55@huawei.com>]

On 2021/9/27 18:12, Daniel P. Berrangé wrote:
> On Sun, Sep 26, 2021 at 04:45:38PM +0800, Yanan Wang wrote:
>> Currently the only difference between smp_parse and pc_smp_parse
>> is the support of dies parameter and the related error reporting.
>> With some arch compat variables like "bool dies_supported", we can
>> make smp_parse generic enough for all arches and the PC specific
>> one can be removed.
>>
>> Making smp_parse() generic enough can reduce code duplication and
>> ease the code maintenance, and also allows extending the topology
>> with more arch specific members (e.g., clusters) in the future.
>>
>> Suggested-by: Andrew Jones <drjones@redhat.com>
>> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
>> Reviewed-by: Andrew Jones <drjones@redhat.com>
>> ---
>>   hw/core/machine.c   | 110 ++++++++++++++++++++++++++++++++++++--------
>>   hw/i386/pc.c        |  84 +--------------------------------
>>   include/hw/boards.h |   9 ++++
>>   3 files changed, 100 insertions(+), 103 deletions(-)
>>
>> diff --git a/hw/core/machine.c b/hw/core/machine.c
>> index a21fcd7700..4b5c943f8e 100644
>> --- a/hw/core/machine.c
>> +++ b/hw/core/machine.c
>> @@ -15,6 +15,7 @@
>>   #include "qapi/qmp/qerror.h"
>>   #include "sysemu/replay.h"
>>   #include "qemu/units.h"
>> +#include "qemu/cutils.h"
>>   #include "hw/boards.h"
>>   #include "hw/loader.h"
>>   #include "qapi/error.h"
>> @@ -746,20 +747,87 @@ void machine_set_cpu_numa_node(MachineState *machine,
>>       }
>>   }
>>   
>> +static char *cpu_topology_hierarchy(MachineState *ms)
>> +{
>> +    MachineClass *mc = MACHINE_GET_CLASS(ms);
>> +    SMPCompatProps *smp_props = &mc->smp_props;
>> +    char topo_msg[256] = "";
>> +
>> +    /*
>> +     * Topology members should be ordered from the largest to the smallest.
>> +     * Concept of sockets/cores/threads is supported by default and will be
>> +     * reported in the hierarchy. Unsupported members will not be reported.
>> +     */
>> +    g_autofree char *sockets_msg = g_strdup_printf(
>> +            " * sockets (%u)", ms->smp.sockets);
>> +    pstrcat(topo_msg, sizeof(topo_msg), sockets_msg);
>> +
>> +    if (smp_props->dies_supported) {
>> +        g_autofree char *dies_msg = g_strdup_printf(
>> +                " * dies (%u)", ms->smp.dies);
>> +        pstrcat(topo_msg, sizeof(topo_msg), dies_msg);
>> +    }
>> +
>> +    g_autofree char *cores_msg = g_strdup_printf(
>> +            " * cores (%u)", ms->smp.cores);
>> +    pstrcat(topo_msg, sizeof(topo_msg), cores_msg);
>> +
>> +    g_autofree char *threads_msg = g_strdup_printf(
>> +            " * threads (%u)", ms->smp.threads);
>> +    pstrcat(topo_msg, sizeof(topo_msg), threads_msg);
>> +
>> +    return g_strdup_printf("%s", topo_msg + 3);
>> +}
> Mixing g_strdup_printf + pstrcat + fixed buffer is quite
> unpleasant. This method is begging to use 'GString' APIs
> for formatting.
>
Indeed, GString seems to be the ideal choice for this. It's
my bad not thinking about usage of it at the beginning.
I will update this patch in v11. Thanks for the suggestion.

Thanks,
Yanan