Re: [Qemu-devel] [for-2.1 PATCH v2 2/2] i386/acpi-build: support hotplug of VCPU with APIC ID 0xFF

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Mar 17, 2014 at 05:05:17PM +0100, Laszlo Ersek wrote:
> Building on the previous patch, raise the maximal count of processor
> objects / NTFY branches / CPON elements from 255 to 256. This allows the
> VCPU with APIC ID 0xFF to be hotplugged.
> 
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>


I note that we still have:
    if (endvalue >= MAX_CPUMASK_BITS) {
        endvalue = MAX_CPUMASK_BITS - 1;
        fprintf(stderr,
            "qemu: NUMA: A max of %d VCPUs are supported\n",
             MAX_CPUMASK_BITS);
    }
and MAX_CPUMASK_BITS is 255.

Seems inconsistent?

> ---
>  hw/i386/acpi-build.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 2bbefb5..c9fe07f 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -999,11 +999,16 @@ build_ssdt(GArray *table_data, GArray *linker,
>             AcpiCpuInfo *cpu, AcpiPmInfo *pm, AcpiMiscInfo *misc,
>             PcPciInfo *pci, PcGuestInfo *guest_info)
>  {
> -    int acpi_cpus = MIN(0xff, guest_info->apic_id_limit);
> +    unsigned acpi_cpus = guest_info->apic_id_limit;
>      int ssdt_start = table_data->len;
>      uint8_t *ssdt_ptr;
>      int i;
>  
> +    /* The current AML generator can cover the APIC ID range [0..255],
> +     * inclusive, for VCPU hotplug. */
> +    QEMU_BUILD_BUG_ON(ACPI_CPU_HOTPLUG_ID_LIMIT > 256);
> +    g_assert(acpi_cpus <= ACPI_CPU_HOTPLUG_ID_LIMIT);
> +
>      /* Copy header and patch values in the S3_ / S4_ / S5_ packages */
>      ssdt_ptr = acpi_data_push(table_data, sizeof(ssdp_misc_aml));
>      memcpy(ssdt_ptr, ssdp_misc_aml, sizeof(ssdp_misc_aml));
> -- 
> 1.8.3.1