Re: [Qemu-devel] [PATCH v2 05/31] vl.c: extend -m option to support options for memory hotplug

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

On Tue, May 20, 2014 at 05:15:08PM +0200, Igor Mammedov wrote:
> Add following parameters:
>   "slots" - total number of hotplug memory slots
>   "maxmem" - maximum possible memory
> 
> "slots" and "maxmem" should go in pair and "maxmem" should be greater
> than "mem" for memory hotplug to be enabled.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>

Also, it's a bug to mix this with a compat machine type, right?
Maybe best to fail initialization if users try this.

> ---
> v4:
>  - store maxmem & slots values in MachineState
> v3:
>  - store maxmem & slots values in QEMUMachineInitArgs
> v2:
>  - rebased on top of the latest "vl: convert -m to QemuOpts"
> ---
>  include/hw/boards.h |    3 ++-
>  qemu-options.hx     |    9 ++++++---
>  vl.c                |   51 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 59 insertions(+), 4 deletions(-)
> 
> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index b62de4a..f6fbbe1 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -8,7 +8,6 @@
>  #include "hw/qdev.h"
>  #include "qom/object.h"
>  
> -
>  typedef struct MachineState MachineState;
>  
>  typedef void QEMUMachineInitFunc(MachineState *ms);
> @@ -113,6 +112,8 @@ struct MachineState {
>      char *firmware;
>  
>      ram_addr_t ram_size;
> +    ram_addr_t maxram_size;
> +    uint64_t   ram_slots;
>      const char *boot_order;
>      const char *kernel_filename;
>      const char *kernel_cmdline;
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 781af14..c6411c4 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -210,17 +210,20 @@ use is discouraged as it may be removed from future versions.
>  ETEXI
>  
>  DEF("m", HAS_ARG, QEMU_OPTION_m,
> -    "-m [size=]megs\n"
> +    "-m[emory] [size=]megs[,slots=n,maxmem=size]\n"
>      "                configure guest RAM\n"
>      "                size: initial amount of guest memory (default: "
> -    stringify(DEFAULT_RAM_SIZE) "MiB)\n",
> +    stringify(DEFAULT_RAM_SIZE) "MiB)\n"
> +    "                slots: number of hotplug slots (default: none)\n"
> +    "                maxmem: maximum amount of guest memory (default: none)\n",
>      QEMU_ARCH_ALL)
>  STEXI
>  @item -m [size=]@var{megs}
>  @findex -m
>  Set virtual RAM size to @var{megs} megabytes. Default is 128 MiB.  Optionally,
>  a suffix of ``M'' or ``G'' can be used to signify a value in megabytes or
> -gigabytes respectively.
> +gigabytes respectively. Optional pair @var{slots}, @var{maxmem} could be used
> +to set amount of hotluggable memory slots and possible maximum amount of memory.
>  ETEXI
>  
>  DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath,
> diff --git a/vl.c b/vl.c
> index 8fd4ed9..9fb6fa4 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -520,6 +520,14 @@ static QemuOptsList qemu_mem_opts = {
>              .name = "size",
>              .type = QEMU_OPT_SIZE,
>          },
> +        {
> +            .name = "slots",
> +            .type = QEMU_OPT_NUMBER,
> +        },
> +        {
> +            .name = "maxmem",
> +            .type = QEMU_OPT_SIZE,
> +        },
>          { /* end of list */ }
>      },
>  };
> @@ -2989,6 +2997,8 @@ int main(int argc, char **argv, char **envp)
>      const char *trace_file = NULL;
>      const ram_addr_t default_ram_size = (ram_addr_t)DEFAULT_RAM_SIZE *
>                                          1024 * 1024;
> +    ram_addr_t maxram_size = default_ram_size;
> +    uint64_t ram_slots = 0;
>  
>      atexit(qemu_run_exit_notifiers);
>      error_set_progname(argv[0]);
> @@ -3324,6 +3334,7 @@ int main(int argc, char **argv, char **envp)
>              case QEMU_OPTION_m: {
>                  uint64_t sz;
>                  const char *mem_str;
> +                const char *maxmem_str, *slots_str;
>  
>                  opts = qemu_opts_parse(qemu_find_opts("memory"),
>                                         optarg, 1);
> @@ -3365,6 +3376,44 @@ int main(int argc, char **argv, char **envp)
>                      error_report("ram size too large");
>                      exit(EXIT_FAILURE);
>                  }
> +
> +                maxmem_str = qemu_opt_get(opts, "maxmem");
> +                slots_str = qemu_opt_get(opts, "slots");
> +                if (maxmem_str && slots_str) {
> +                    uint64_t slots;
> +
> +                    sz = qemu_opt_get_size(opts, "maxmem", 0);
> +                    if (sz < ram_size) {
> +                        fprintf(stderr, "qemu: invalid -m option value: maxmem "
> +                                "(%" PRIu64 ") <= initial memory (%"
> +                                PRIu64 ")\n", sz, ram_size);
> +                        exit(EXIT_FAILURE);
> +                    }
> +
> +                    slots = qemu_opt_get_number(opts, "slots", 0);
> +                    if ((sz > ram_size) && !slots) {
> +                        fprintf(stderr, "qemu: invalid -m option value: maxmem "
> +                                "(%" PRIu64 ") more than initial memory (%"
> +                                PRIu64 ") but no hotplug slots where "
> +                                "specified\n", sz, ram_size);
> +                        exit(EXIT_FAILURE);
> +                    }
> +
> +                    if ((sz <= ram_size) && slots) {
> +                        fprintf(stderr, "qemu: invalid -m option value:  %"
> +                                PRIu64 " hotplug slots where specified but "
> +                                "maxmem (%" PRIu64 ") <= initial memory (%"
> +                                PRIu64 ")\n", slots, sz, ram_size);
> +                        exit(EXIT_FAILURE);
> +                    }
> +                    maxram_size = sz;
> +                    ram_slots = slots;
> +                } else if ((!maxmem_str && slots_str) ||
> +                           (maxmem_str && !slots_str)) {
> +                    fprintf(stderr, "qemu: invalid -m option value: missing "
> +                            "'%s' option\n", slots_str ? "maxmem" : "slots");
> +                    exit(EXIT_FAILURE);
> +                }
>                  break;
>              }
>  #ifdef CONFIG_TPM
> @@ -4422,6 +4471,8 @@ int main(int argc, char **argv, char **envp)
>      qdev_machine_init();
>  
>      current_machine->ram_size = ram_size;
> +    current_machine->maxram_size = maxram_size;
> +    current_machine->ram_slots = ram_slots;
>      current_machine->boot_order = boot_order;
>      current_machine->kernel_filename = kernel_filename;
>      current_machine->kernel_cmdline = kernel_cmdline;
> -- 
> 1.7.1