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Re: [RFC PATCH 3/3] softmmu/vl: Add qemu_cpu_opts QemuOptsList


From: LIU Zhiwei
Subject: Re: [RFC PATCH 3/3] softmmu/vl: Add qemu_cpu_opts QemuOptsList
Date: Mon, 28 Aug 2023 10:06:45 +0800
User-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.14.0

Hi Drew

On 2023/8/25 23:58, Andrew Jones wrote:
On Fri, Aug 25, 2023 at 08:16:51PM +0800, LIU Zhiwei wrote:
This make the cpu works the similar way like the -device option.

For device option,
"""
./qemu-system-riscv64 -device e1000,help
e1000 options:
   acpi-index=<uint32>    -  (default: 0)
   addr=<int32>           - Slot and optional function number, example: 06.0 or 
06 (default: -1)
   autonegotiation=<bool> - on/off (default: true)
   bootindex=<int32>
   extra_mac_registers=<bool> - on/off (default: true)
   failover_pair_id=<str>
"""

After this patch, the cpu can output its configurations,
"""
./qemu-system-riscv64 -cpu rv64,help
Enable extension:
        
rv64imafdch_zicbom_zicboz_zicsr_zifencei_zihintpause_zawrs_zfa_zba_zbb_zbc_zbs_sstc_svadu
"""
I recommend we make it more similar to -device and list the properties
(not just extensions). Besides a listing being easier to read than the
isa string format, listing properties would also output, e.g.

  cbom_blocksize=<uint16>    -  (default: 64)

which would also be helpful.

I agree that we should add more outputs in cpu_list_props to aid the understanding of the isa string output. And let users know what they should explicitly added the -cpu command line.

I will refer to the -device option output. However, The -device option is not enough for cpu model.

"""

qemu-system-riscv64 -device rv64-riscv-cpu,zba=false,help

rv64-riscv-cpu options:
  Zawrs=<bool>           -  (default: true)
  Zfa=<bool>             -  (default: true)
  Zfh=<bool>             -  (default: false)
  Zfhmin=<bool>          -  (default: false)
  Zicsr=<bool>           -  (default: true)
  Zifencei=<bool>        -  (default: true)
  Zihintpause=<bool>     -  (default: true)
  Zve32f=<bool>          -  (default: false)
  Zve64d=<bool>          -  (default: false)
  Zve64f=<bool>          -  (default: false)
  a=<bool>               - Atomic instructions
  c=<bool>               - Compressed instructions
  cbom_blocksize=<uint16> -  (default: 64)
  cboz_blocksize=<uint16> -  (default: 64)
  d=<bool>               - Double-precision float point

  ...

 unnamed-gpio-in[0]=<child<irq>>
  unnamed-gpio-in[10]=<child<irq>>
  unnamed-gpio-in[11]=<child<irq>>
  unnamed-gpio-in[12]=<child<irq>>
  unnamed-gpio-in[13]=<child<irq>>
  unnamed-gpio-in[14]=<child<irq>>

...

memory=<link<memory-region>>

...

start-powered-off=<bool>

...

  v=<bool>               - Vector operations
  vext_spec=<str>

...

  zba=<bool>             -  (default: true)
  zbb=<bool>             -  (default: true)
  zbc=<bool>             -  (default: true)
  zbkb=<bool>            -  (default: false)

...

"""

1) IMHO, unnamed-gpio-in and start-powered-off exposing to users is meaningless.

2) Option like v and vext_spec doesn't output the defalut value.

3) The zba=false  in command line can't reflect  in the output.

That is the reason  why I want to add a new API cpu_list_props.

Thanks,
Zhwei


Thanks,
drew

Signed-off-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
---
  cpu.c                 |  2 +-
  include/hw/core/cpu.h | 11 +++++++++++
  softmmu/vl.c          | 35 +++++++++++++++++++++++++++++++++++
  3 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/cpu.c b/cpu.c
index 03a313cd72..712bd02684 100644
--- a/cpu.c
+++ b/cpu.c
@@ -257,7 +257,7 @@ void cpu_exec_initfn(CPUState *cpu)
  #endif
  }
-static const char *cpu_type_by_name(const char *cpu_model)
+const char *cpu_type_by_name(const char *cpu_model)
  {
      ObjectClass *oc;
      const char *cpu_type;
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index fdcbe87352..49d41afdfa 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -657,6 +657,17 @@ CPUState *cpu_create(const char *typename);
   */
  const char *parse_cpu_option(const char *cpu_option);
+/**
+ * cpu_type_by_name:
+ * @cpu_model: The -cpu command line model name.
+ *
+ * Looks up type name by the -cpu command line model name
+ *
+ * Returns: type name of CPU or prints error and terminates process
+ *          if an error occurred.
+ */
+const char *cpu_type_by_name(const char *cpu_model);
+
  /**
   * cpu_has_work:
   * @cpu: The vCPU to check.
diff --git a/softmmu/vl.c b/softmmu/vl.c
index b0b96f67fa..bc30f3954d 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -218,6 +218,15 @@ static struct {
      { .driver = "virtio-vga-gl",        .flag = &default_vga       },
  };
+static QemuOptsList qemu_cpu_opts = {
+    .name = "cpu",
+    .implied_opt_name = "cpu_model",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_cpu_opts.head),
+    .desc = {
+        { /* end of list */ }
+    },
+};
+
  static QemuOptsList qemu_rtc_opts = {
      .name = "rtc",
      .head = QTAILQ_HEAD_INITIALIZER(qemu_rtc_opts.head),
@@ -1140,6 +1149,21 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts, 
Error **errp)
      return 0;
  }
+static int cpu_help_func(void *opaque, QemuOpts *opts, Error **errp)
+{
+    const char *cpu_model, *cpu_type;
+    cpu_model = qemu_opt_get(opts, "cpu_model");
+    if (!cpu_model) {
+        return 1;
+    }
+    if (!qemu_opt_has_help_opt(opts)) {
+        return 0;
+    }
+    cpu_type = cpu_type_by_name(cpu_model);
+    list_cpu_props((CPUState *)object_new(cpu_type));
+    return 1;
+}
+
  static int device_help_func(void *opaque, QemuOpts *opts, Error **errp)
  {
      return qdev_device_help(opts);
@@ -2467,6 +2491,11 @@ static void qemu_process_help_options(void)
          exit(0);
      }
+ if (qemu_opts_foreach(qemu_find_opts("cpu"),
+                          cpu_help_func, NULL, NULL)) {
+        exit(0);
+    }
+
      if (qemu_opts_foreach(qemu_find_opts("device"),
                            device_help_func, NULL, NULL)) {
          exit(0);
@@ -2680,6 +2709,7 @@ void qemu_init(int argc, char **argv)
      qemu_add_drive_opts(&bdrv_runtime_opts);
      qemu_add_opts(&qemu_chardev_opts);
      qemu_add_opts(&qemu_device_opts);
+    qemu_add_opts(&qemu_cpu_opts);
      qemu_add_opts(&qemu_netdev_opts);
      qemu_add_opts(&qemu_nic_opts);
      qemu_add_opts(&qemu_net_opts);
@@ -2756,6 +2786,11 @@ void qemu_init(int argc, char **argv)
              case QEMU_OPTION_cpu:
                  /* hw initialization will check this */
                  cpu_option = optarg;
+                opts = qemu_opts_parse_noisily(qemu_find_opts("cpu"),
+                                               optarg, true);
+                if (!opts) {
+                    exit(1);
+                }
                  break;
              case QEMU_OPTION_hda:
              case QEMU_OPTION_hdb:
--
2.17.1




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