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Re: [PATCH] target/riscv: deprecate capital 'Z' CPU properties

From: Daniel Henrique Barboza
Subject: Re: [PATCH] target/riscv: deprecate capital 'Z' CPU properties
Date: Mon, 9 Oct 2023 08:30:56 -0300
User-agent: Mozilla Thunderbird 

On 10/8/23 22:39, Alistair Francis wrote:

On Sun, Oct 8, 2023 at 3:15 AM Daniel Henrique Barboza
<dbarboza@ventanamicro.com> wrote:


At this moment there are eleven CPU extension properties that starts
with capital 'Z': Zifencei, Zicsr, Zihintntl, Zihintpause, Zawrs, Zfa,
Zfh, Zfhmin, Zve32f, Zve64f and Zve64d. All other extensions are named
with lower-case letters.

We want all properties to be named with lower-case letters since it's
consistent with the riscv-isa string that we create in the FDT. Having
these 11 properties to be exceptions can be confusing.

Deprecate all of them. Create their lower-case counterpart to be used as
maintained CPU properties. When trying to use any deprecated property a
warning message will be displayed, recommending users to switch to the
lower-case variant:

./build/qemu-system-riscv64 -M virt -cpu rv64,Zifencei=true --nographic
qemu-system-riscv64: warning: CPU property 'Zifencei' is deprecated. Please use 
'zifencei' instead

This will give users some time to change their scripts before we remove
the capital 'Z' properties entirely.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>


Thanks!

Applied to riscv-to-apply.next

Alistair


I just sent a v2 with the doc fix Drew mentioned. Feel free to either pick the 
v2 or
amend this one in-tree. Whatever is more convenient for you.



Thanks,

Daniel




---
  docs/about/deprecated.rst  | 23 ++++++++++++++++++++++
  target/riscv/cpu.c         | 39 +++++++++++++++++++++++++++-----------
  target/riscv/cpu.h         |  1 +
  target/riscv/tcg/tcg-cpu.c | 31 +++++++++++++++++++++++++++++-
  4 files changed, 82 insertions(+), 12 deletions(-)

diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
index 694b878f36..331f10f930 100644
--- a/docs/about/deprecated.rst
+++ b/docs/about/deprecated.rst
@@ -378,6 +378,29 @@ of generic CPUs: rv32 and rv64 as default CPUs and 'max' 
as a feature complete
  CPU for both 32 and 64 bit builds. Users are then discouraged to use the 'any'
  CPU type starting in 8.2.

+RISC-V CPU properties which start with with capital 'Z' (since 8.2)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+All RISC-V CPU properties which start with capital 'Z' are being deprecated
+starting in 8.2. The reason is that they were wrongly added with capital 'Z'
+in the past. CPU properties were later added with lower-case names, which
+is the format we want to use from now on.
+
+Users which try to use these deprecated properties will receive a warning
+recommending to switch to their stable counterparts:
+
+- "Zifencei" should be replaced with "zifencei"
+- "Zicsr" should be replaced with "zicsr"
+- "Zihintntl" should be replaced with "zihintntl"
+- "Zihintpause" should be replaced with "zihintpause"
+- "Zawrs" should be replaced with "zawrs"
+- "Zfa" should be replaced with "zfa"
+- "Zfh" should be replaced with "zfh"
+- "Zfhmin" should be replaced with "zfhmin"
+- "Zve32f" should be replaced with "zve32f"
+- "Zve64f" should be replaced with "zve64f"
+- "Zve64d" should be replaced with "zve64d"
+
  Block device options
  ''''''''''''''''''''

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 521bb88538..1cdc3d2609 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -1246,17 +1246,17 @@ const char *riscv_get_misa_ext_description(uint32_t bit)
  const RISCVCPUMultiExtConfig riscv_cpu_extensions[] = {
      /* Defaults for standard extensions */
      MULTI_EXT_CFG_BOOL("sscofpmf", ext_sscofpmf, false),
-    MULTI_EXT_CFG_BOOL("Zifencei", ext_ifencei, true),
-    MULTI_EXT_CFG_BOOL("Zicsr", ext_icsr, true),
-    MULTI_EXT_CFG_BOOL("Zihintntl", ext_zihintntl, true),
-    MULTI_EXT_CFG_BOOL("Zihintpause", ext_zihintpause, true),
-    MULTI_EXT_CFG_BOOL("Zawrs", ext_zawrs, true),
-    MULTI_EXT_CFG_BOOL("Zfa", ext_zfa, true),
-    MULTI_EXT_CFG_BOOL("Zfh", ext_zfh, false),
-    MULTI_EXT_CFG_BOOL("Zfhmin", ext_zfhmin, false),
-    MULTI_EXT_CFG_BOOL("Zve32f", ext_zve32f, false),
-    MULTI_EXT_CFG_BOOL("Zve64f", ext_zve64f, false),
-    MULTI_EXT_CFG_BOOL("Zve64d", ext_zve64d, false),
+    MULTI_EXT_CFG_BOOL("zifencei", ext_ifencei, true),
+    MULTI_EXT_CFG_BOOL("zicsr", ext_icsr, true),
+    MULTI_EXT_CFG_BOOL("zihintntl", ext_zihintntl, true),
+    MULTI_EXT_CFG_BOOL("zihintpause", ext_zihintpause, true),
+    MULTI_EXT_CFG_BOOL("zawrs", ext_zawrs, true),
+    MULTI_EXT_CFG_BOOL("zfa", ext_zfa, true),
+    MULTI_EXT_CFG_BOOL("zfh", ext_zfh, false),
+    MULTI_EXT_CFG_BOOL("zfhmin", ext_zfhmin, false),
+    MULTI_EXT_CFG_BOOL("zve32f", ext_zve32f, false),
+    MULTI_EXT_CFG_BOOL("zve64f", ext_zve64f, false),
+    MULTI_EXT_CFG_BOOL("zve64d", ext_zve64d, false),
      MULTI_EXT_CFG_BOOL("sstc", ext_sstc, true),

      MULTI_EXT_CFG_BOOL("smstateen", ext_smstateen, false),
@@ -1349,6 +1349,23 @@ const RISCVCPUMultiExtConfig 
riscv_cpu_experimental_exts[] = {
      DEFINE_PROP_END_OF_LIST(),
  };

+/* Deprecated entries marked for future removal */
+const RISCVCPUMultiExtConfig riscv_cpu_deprecated_exts[] = {
+    MULTI_EXT_CFG_BOOL("Zifencei", ext_ifencei, true),
+    MULTI_EXT_CFG_BOOL("Zicsr", ext_icsr, true),
+    MULTI_EXT_CFG_BOOL("Zihintntl", ext_zihintntl, true),
+    MULTI_EXT_CFG_BOOL("Zihintpause", ext_zihintpause, true),
+    MULTI_EXT_CFG_BOOL("Zawrs", ext_zawrs, true),
+    MULTI_EXT_CFG_BOOL("Zfa", ext_zfa, true),
+    MULTI_EXT_CFG_BOOL("Zfh", ext_zfh, false),
+    MULTI_EXT_CFG_BOOL("Zfhmin", ext_zfhmin, false),
+    MULTI_EXT_CFG_BOOL("Zve32f", ext_zve32f, false),
+    MULTI_EXT_CFG_BOOL("Zve64f", ext_zve64f, false),
+    MULTI_EXT_CFG_BOOL("Zve64d", ext_zve64d, false),
+
+    DEFINE_PROP_END_OF_LIST(),
+};
+
  Property riscv_cpu_options[] = {
      DEFINE_PROP_UINT8("pmu-num", RISCVCPU, cfg.pmu_num, 16),

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 3f11e69223..e98f5de32e 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -722,6 +722,7 @@ typedef struct RISCVCPUMultiExtConfig {
  extern const RISCVCPUMultiExtConfig riscv_cpu_extensions[];
  extern const RISCVCPUMultiExtConfig riscv_cpu_vendor_exts[];
  extern const RISCVCPUMultiExtConfig riscv_cpu_experimental_exts[];
+extern const RISCVCPUMultiExtConfig riscv_cpu_deprecated_exts[];
  extern Property riscv_cpu_options[];

  typedef struct isa_ext_data {
diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
index 08b806dc07..00676593f7 100644
--- a/target/riscv/tcg/tcg-cpu.c
+++ b/target/riscv/tcg/tcg-cpu.c
@@ -732,6 +732,25 @@ static void riscv_cpu_add_misa_properties(Object *cpu_obj)
      }
  }

+static bool cpu_ext_is_deprecated(const char *ext_name)
+{
+    return isupper(ext_name[0]);
+}
+
+/*
+ * String will be allocated in the heap. Caller is responsible
+ * for freeing it.
+ */
+static char *cpu_ext_to_lower(const char *ext_name)
+{
+    char *ret = g_malloc0(strlen(ext_name) + 1);
+
+    strcpy(ret, ext_name);
+    ret[0] = tolower(ret[0]);
+
+    return ret;
+}
+
  static void cpu_set_multi_ext_cfg(Object *obj, Visitor *v, const char *name,
                                    void *opaque, Error **errp)
  {
@@ -744,6 +763,13 @@ static void cpu_set_multi_ext_cfg(Object *obj, Visitor *v, 
const char *name,
          return;
      }

+    if (cpu_ext_is_deprecated(multi_ext_cfg->name)) {
+        g_autofree char *lower = cpu_ext_to_lower(multi_ext_cfg->name);
+
+        warn_report("CPU property '%s' is deprecated. Please use '%s' instead",
+                    multi_ext_cfg->name, lower);
+    }
+
      g_hash_table_insert(multi_ext_user_opts,
                          GUINT_TO_POINTER(multi_ext_cfg->offset),
                          (gpointer)value);
@@ -777,13 +803,14 @@ static void cpu_add_multi_ext_prop(Object *cpu_obj,
                                     const RISCVCPUMultiExtConfig *multi_cfg)
  {
      bool generic_cpu = riscv_cpu_is_generic(cpu_obj);
+    bool deprecated_ext = cpu_ext_is_deprecated(multi_cfg->name);

      object_property_add(cpu_obj, multi_cfg->name, "bool",
                          cpu_get_multi_ext_cfg,
                          cpu_set_multi_ext_cfg,
                          NULL, (void *)multi_cfg);

-    if (!generic_cpu) {
+    if (!generic_cpu || deprecated_ext) {
          return;
      }

@@ -826,6 +853,8 @@ static void riscv_cpu_add_user_properties(Object *obj)
      riscv_cpu_add_multiext_prop_array(obj, riscv_cpu_vendor_exts);
      riscv_cpu_add_multiext_prop_array(obj, riscv_cpu_experimental_exts);

+    riscv_cpu_add_multiext_prop_array(obj, riscv_cpu_deprecated_exts);
+
      for (Property *prop = riscv_cpu_options; prop && prop->name; prop++) {
          qdev_property_add_static(DEVICE(obj), prop);
      }
--
2.41.0
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