On Wed, 10 Apr 2019 23:10:25 +0000 Alistair Francis <alistair.fran...@wdc.com> wrote:
> If a user specifies a CPU that we don't understand then we want to fall > back to a CPU generated from the ISA string. It might look like a nice thing to do at the beginning, but fallbacks become a source of pain in future and get in the way of refactorings if there is a promise to maintain defaults (fallbacks) stable. I suggest do not fallback to anything, just fail cleanly with informative error telling users what is wrong and let user fix their invalid CLI in the first place. > At the moment the generated CPU is assumed to be a privledge spec > version 1.10 CPU with an MMU. This can be changed in the future. > > Signed-off-by: Alistair Francis <alistair.fran...@wdc.com> > --- > v3: > - Ensure a minimal length so we don't run off the end of the string. > - Don't parse the rv32/rv64 in the loop > target/riscv/cpu.c | 101 ++++++++++++++++++++++++++++++++++++++++++++- > target/riscv/cpu.h | 2 + > 2 files changed, 102 insertions(+), 1 deletion(-) > > diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c > index d61bce6d55..27be9e412a 100644 > --- a/target/riscv/cpu.c > +++ b/target/riscv/cpu.c > @@ -19,6 +19,7 @@ > > #include "qemu/osdep.h" > #include "qemu/log.h" > +#include "qemu/error-report.h" > #include "cpu.h" > #include "exec/exec-all.h" > #include "qapi/error.h" > @@ -103,6 +104,99 @@ static void set_resetvec(CPURISCVState *env, int > resetvec) > #endif > } > > +static void riscv_generate_cpu_init(Object *obj) > +{ > + RISCVCPU *cpu = RISCV_CPU(obj); > + CPURISCVState *env = &cpu->env; > + RISCVCPUClass *mcc = RISCV_CPU_GET_CLASS(cpu); > + const char *riscv_cpu = mcc->isa_str; > + target_ulong target_misa = 0; > + target_ulong rvxlen = 0; > + int i; > + bool valid = false; > + > + /* > + * We need at least 5 charecters for the string to be valid. Check that > + * now so we can be lazier later. > + */ > + if (strlen(riscv_cpu) < 5) { > + error_report("'%s' does not appear to be a valid RISC-V ISA string", > + riscv_cpu); > + exit(1); > + } > + > + if (riscv_cpu[0] == 'r' && riscv_cpu[1] == 'v') { > + /* Starts with "rv" */ > + if (riscv_cpu[2] == '3' && riscv_cpu[3] == '2') { > + valid = true; > + rvxlen = RV32; > + } > + if (riscv_cpu[2] == '6' && riscv_cpu[3] == '4') { > + valid = true; > + rvxlen = RV64; > + } > + } > + > + if (!valid) { > + error_report("'%s' does not appear to be a valid RISC-V CPU", > + riscv_cpu); > + exit(1); > + } > + > + for (i = 4; i < strlen(riscv_cpu); i++) { > + switch (riscv_cpu[i]) { > + case 'i': > + if (target_misa & RVE) { > + error_report("I and E extensions are incompatible"); > + exit(1); > + } > + target_misa |= RVI; > + continue; > + case 'e': > + if (target_misa & RVI) { > + error_report("I and E extensions are incompatible"); > + exit(1); > + } > + target_misa |= RVE; > + continue; > + case 'g': > + target_misa |= RVI | RVM | RVA | RVF | RVD; > + continue; > + case 'm': > + target_misa |= RVM; > + continue; > + case 'a': > + target_misa |= RVA; > + continue; > + case 'f': > + target_misa |= RVF; > + continue; > + case 'd': > + target_misa |= RVD; > + continue; > + case 'c': > + target_misa |= RVC; > + continue; > + case 's': > + target_misa |= RVS; > + continue; > + case 'u': > + target_misa |= RVU; > + continue; > + default: > + warn_report("QEMU does not support the %c extension", > + riscv_cpu[i]); > + continue; > + } > + } > + > + set_misa(env, rvxlen | target_misa); > + set_versions(env, USER_VERSION_2_02_0, PRIV_VERSION_1_10_0); > + set_resetvec(env, DEFAULT_RSTVEC); > + set_feature(env, RISCV_FEATURE_MMU); > + set_feature(env, RISCV_FEATURE_PMP); > +} > + > static void riscv_any_cpu_init(Object *obj) > { > CPURISCVState *env = &RISCV_CPU(obj)->env; > @@ -178,6 +272,7 @@ static void rv64imacu_nommu_cpu_init(Object *obj) > static ObjectClass *riscv_cpu_class_by_name(const char *cpu_model) > { > ObjectClass *oc; > + RISCVCPUClass *mcc; > char *typename; > char **cpuname; > > @@ -188,7 +283,10 @@ static ObjectClass *riscv_cpu_class_by_name(const char > *cpu_model) > g_free(typename); > if (!oc || !object_class_dynamic_cast(oc, TYPE_RISCV_CPU) || > object_class_is_abstract(oc)) { > - return NULL; > + /* No CPU found, try the generic CPU and pass in the ISA string */ > + oc = object_class_by_name(TYPE_RISCV_CPU_GEN); > + mcc = RISCV_CPU_CLASS(oc); > + mcc->isa_str = g_strdup(cpu_model); > } > return oc; > } > @@ -440,6 +538,7 @@ static const TypeInfo riscv_cpu_type_infos[] = { > .class_init = riscv_cpu_class_init, > }, > DEFINE_CPU(TYPE_RISCV_CPU_ANY, riscv_any_cpu_init), > + DEFINE_CPU(TYPE_RISCV_CPU_GEN, riscv_generate_cpu_init), > #if defined(TARGET_RISCV32) > DEFINE_CPU(TYPE_RISCV_CPU_RV32GCSU_V1_09_1, > rv32gcsu_priv1_09_1_cpu_init), > DEFINE_CPU(TYPE_RISCV_CPU_RV32GCSU_V1_10_0, > rv32gcsu_priv1_10_0_cpu_init), > diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h > index 20bce8742e..453108a855 100644 > --- a/target/riscv/cpu.h > +++ b/target/riscv/cpu.h > @@ -48,6 +48,7 @@ > #define CPU_RESOLVING_TYPE TYPE_RISCV_CPU > > #define TYPE_RISCV_CPU_ANY RISCV_CPU_TYPE_NAME("any") > +#define TYPE_RISCV_CPU_GEN RISCV_CPU_TYPE_NAME("rv*") > #define TYPE_RISCV_CPU_RV32GCSU_V1_09_1 > RISCV_CPU_TYPE_NAME("rv32gcsu-v1.9.1") > #define TYPE_RISCV_CPU_RV32GCSU_V1_10_0 > RISCV_CPU_TYPE_NAME("rv32gcsu-v1.10.0") > #define TYPE_RISCV_CPU_RV32IMACU_NOMMU > RISCV_CPU_TYPE_NAME("rv32imacu-nommu") > @@ -211,6 +212,7 @@ typedef struct RISCVCPUClass { > /*< public >*/ > DeviceRealize parent_realize; > void (*parent_reset)(CPUState *cpu); > + const char *isa_str; > } RISCVCPUClass; > > /**