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Re: [RISC-V][tech-server-platform] [RISC-V][tech-server-soc] [RFC 2/2] t


From: Heinrich Schuchardt
Subject: Re: [RISC-V][tech-server-platform] [RISC-V][tech-server-soc] [RFC 2/2] target/riscv: Add server platform reference cpu
Date: Thu, 7 Mar 2024 13:17:21 +0100
User-agent: Mozilla Thunderbird

On 07.03.24 08:36, Wu, Fei2 wrote:
On 3/6/2024 9:26 PM, Wu, Fei wrote:
On 3/5/2024 1:58 PM, Wu, Fei wrote:
On 3/5/2024 3:43 AM, Daniel Henrique Barboza wrote:


On 3/4/24 07:25, Fei Wu wrote:
The harts requirements of RISC-V server platform [1] require RVA23 ISA
profile support, plus Sv48, Svadu, H, Sscofmpf etc. This patch provides
a virt CPU type (rvsp-ref) as compliant as possible.

[1]
https://github.com/riscv-non-isa/riscv-server-platform/blob/main/server_platform_requirements.adoc

Signed-off-by: Fei Wu <fei2.wu@intel.com>
--->   hw/riscv/server_platform_ref.c |  6 +++-
   target/riscv/cpu-qom.h         |  1 +
   target/riscv/cpu.c             | 62 ++++++++++++++++++++++++++++++++++
   3 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/hw/riscv/server_platform_ref.c
b/hw/riscv/server_platform_ref.c
index ae90c4b27a..52ec607cee 100644
--- a/hw/riscv/server_platform_ref.c
+++ b/hw/riscv/server_platform_ref.c
@@ -1205,11 +1205,15 @@ static void
rvsp_ref_machine_class_init(ObjectClass *oc, void *data)
   {
       char str[128];
       MachineClass *mc = MACHINE_CLASS(oc);
+    static const char * const valid_cpu_types[] = {
+        TYPE_RISCV_CPU_RVSP_REF,
+    };
         mc->desc = "RISC-V Server SoC Reference board";
       mc->init = rvsp_ref_machine_init;
       mc->max_cpus = RVSP_CPUS_MAX;
-    mc->default_cpu_type = TYPE_RISCV_CPU_BASE;
+    mc->default_cpu_type = TYPE_RISCV_CPU_RVSP_REF;
+    mc->valid_cpu_types = valid_cpu_types;

I suggest introducing this patch first, then the new machine type that
will use it as a default
CPU. The reason is to facilitate future bisects. If we introduce the
board first, a future bisect
might hit the previous patch, the board will be run using RV64 instead
of the correct CPU, and
we'll have different results because of it.

Good suggestion.

       mc->pci_allow_0_address = true;
       mc->default_nic = "e1000e";
       mc->possible_cpu_arch_ids = riscv_numa_possible_cpu_arch_ids;
diff --git a/target/riscv/cpu-qom.h b/target/riscv/cpu-qom.h
index 3670cfe6d9..adb934d19e 100644
--- a/target/riscv/cpu-qom.h
+++ b/target/riscv/cpu-qom.h
@@ -49,6 +49,7 @@
   #define TYPE_RISCV_CPU_SIFIVE_U54
RISCV_CPU_TYPE_NAME("sifive-u54")
   #define TYPE_RISCV_CPU_THEAD_C906
RISCV_CPU_TYPE_NAME("thead-c906")
   #define TYPE_RISCV_CPU_VEYRON_V1
RISCV_CPU_TYPE_NAME("veyron-v1")
+#define TYPE_RISCV_CPU_RVSP_REF         RISCV_CPU_TYPE_NAME("rvsp-ref")
   #define TYPE_RISCV_CPU_HOST             RISCV_CPU_TYPE_NAME("host")
     OBJECT_DECLARE_CPU_TYPE(RISCVCPU, RISCVCPUClass, RISCV_CPU)
diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 5ff0192c52..bc91be702b 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -2282,6 +2282,67 @@ static void rva22s64_profile_cpu_init(Object *obj)
         RVA22S64.enabled = true;
   }
+
+static void rv64_rvsp_ref_cpu_init(Object *obj)
+{
+    CPURISCVState *env = &RISCV_CPU(obj)->env;
+    RISCVCPU *cpu = RISCV_CPU(obj);
+
+    riscv_cpu_set_misa_ext(env, RVG | RVC | RVS | RVU | RVH | RVV);
+
+    /* FIXME: change to 1.13 */
+    env->priv_ver = PRIV_VERSION_1_12_0;
+
+    /* RVA22U64 */
+    cpu->cfg.mmu = true;
+    cpu->cfg.ext_zifencei = true;
+    cpu->cfg.ext_zicsr = true;
+    cpu->cfg.ext_zicntr = true;
+    cpu->cfg.ext_zihpm = true;
+    cpu->cfg.ext_zihintpause = true;
+    cpu->cfg.ext_zba = true;
+    cpu->cfg.ext_zbb = true;
+    cpu->cfg.ext_zbs = true;
+    cpu->cfg.zic64b = true;
+    cpu->cfg.ext_zicbom = true;
+    cpu->cfg.ext_zicbop = true;
+    cpu->cfg.ext_zicboz = true;
+    cpu->cfg.cbom_blocksize = 64;
+    cpu->cfg.cbop_blocksize = 64;
+    cpu->cfg.cboz_blocksize = 64;
+    cpu->cfg.ext_zfhmin = true;
+    cpu->cfg.ext_zkt = true;

You can change this whole block with:

RVA22U64.enabled = true;


riscv_cpu_add_profiles() will check if we have a profile enabled and, if
that's the
case, we'll enable all its extensions in the CPU.

In the near future, when we implement a proper RVA23 support, we'll be
able to just do
a single RVA23S64.enabled = true in this cpu_init(). But for now we can
at least declare
RVA22U64 (perhaps RVA22S64) support for this CPU.


Hi Daniel,

I'm not sure if it's a regression or the usage has been changed. I'm not
able to use '-cpu rva22s64' on latest qemu (db596ae190).

I did a quick git bisect and found that commit d06f28db6 "target/riscv:
move 'mmu' to riscv_cpu_properties[]" disabled mmu by default, so that
an explicit mmu option should be added to qemu command line like '-cpu
rva22s64,mmu=true', I think rva22s64 should enable it by default.

Thanks,
Fei.

It is nice that the MMU can be disabled. But is there any reason why the MMU should be disabled by default on the virt machine (which typically is used to run an operating system)?

Can we add mmu=true as default to the rv64 CPU?

Best regards

Heinrich



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