Re: [Qemu-devel] [PATCH] Avoid allocating TCG resources in non-TCG mode

[Anthony Liguori <aliguori@us.ibm.com>]

On 08/02/2011 09:10 AM, Jan Kiszka wrote:
> Do not allocate TCG-only resources like the translation buffer when
> running over KVM or XEN. Saves a "few" bytes in the qemu address space
> and is also conceptually cleaner.
>
> Signed-off-by: Jan Kiszka<jan.kiszka@siemens.com>

Applied.  Thanks.

Regards,

Anthony Liguori

> ---
>
> Note: Only tested on x86.
>
>   bsd-user/main.c       |    3 ++-
>   darwin-user/main.c    |    4 ++--
>   exec.c                |   19 ++++++++++++++-----
>   linux-user/main.c     |    3 ++-
>   qemu-common.h         |    5 ++++-
>   target-i386/helper.c  |    4 ++--
>   target-ppc/helper.c   |    4 +++-
>   target-s390x/helper.c |    2 +-
>   vl.c                  |   14 +++++++-------
>   9 files changed, 37 insertions(+), 21 deletions(-)
>
> diff --git a/bsd-user/main.c b/bsd-user/main.c
> index a63b877..cc7d4a3 100644
> --- a/bsd-user/main.c
> +++ b/bsd-user/main.c
> @@ -905,7 +905,8 @@ int main(int argc, char **argv)
>           cpu_model = "any";
>   #endif
>       }
> -    cpu_exec_init_all(0);
> +    tcg_exec_init(0);
> +    cpu_exec_init_all();
>       /* NOTE: we need to init the CPU at this stage to get
>          qemu_host_page_size */
>       env = cpu_init(cpu_model);
> diff --git a/darwin-user/main.c b/darwin-user/main.c
> index 72307ad..1a881a0 100644
> --- a/darwin-user/main.c
> +++ b/darwin-user/main.c
> @@ -852,8 +852,8 @@ int main(int argc, char **argv)
>   #error unsupported CPU
>   #endif
>       }
> -
> -    cpu_exec_init_all(0);
> +    tcg_exec_init(0);
> +    cpu_exec_init_all();
>       /* NOTE: we need to init the CPU at this stage to get
>          qemu_host_page_size */
>       env = cpu_init(cpu_model);
> diff --git a/exec.c b/exec.c
> index 476b507..2658cb2 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -570,16 +570,12 @@ static void code_gen_alloc(unsigned long tb_size)
>   /* Must be called before using the QEMU cpus. 'tb_size' is the size
>      (in bytes) allocated to the translation buffer. Zero means default
>      size. */
> -void cpu_exec_init_all(unsigned long tb_size)
> +void tcg_exec_init(unsigned long tb_size)
>   {
>       cpu_gen_init();
>       code_gen_alloc(tb_size);
>       code_gen_ptr = code_gen_buffer;
>       page_init();
> -#if !defined(CONFIG_USER_ONLY)
> -    memory_map_init();
> -    io_mem_init();
> -#endif
>   #if !defined(CONFIG_USER_ONLY) || !defined(CONFIG_USE_GUEST_BASE)
>       /* There's no guest base to take into account, so go ahead and
>          initialize the prologue now.  */
> @@ -587,6 +583,19 @@ void cpu_exec_init_all(unsigned long tb_size)
>   #endif
>   }
>
> +bool tcg_enabled(void)
> +{
> +    return code_gen_buffer != NULL;
> +}
> +
> +void cpu_exec_init_all(void)
> +{
> +#if !defined(CONFIG_USER_ONLY)
> +    memory_map_init();
> +    io_mem_init();
> +#endif
> +}
> +
>   #if defined(CPU_SAVE_VERSION)&&  !defined(CONFIG_USER_ONLY)
>
>   static int cpu_common_post_load(void *opaque, int version_id)
> diff --git a/linux-user/main.c b/linux-user/main.c
> index 6a8f4bd..8e15474 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -3117,7 +3117,8 @@ int main(int argc, char **argv, char **envp)
>           cpu_model = "any";
>   #endif
>       }
> -    cpu_exec_init_all(0);
> +    tcg_exec_init(0);
> +    cpu_exec_init_all();
>       /* NOTE: we need to init the CPU at this stage to get
>          qemu_host_page_size */
>       env = cpu_init(cpu_model);
> diff --git a/qemu-common.h b/qemu-common.h
> index 1e3c665..3440986 100644
> --- a/qemu-common.h
> +++ b/qemu-common.h
> @@ -273,7 +273,10 @@ typedef struct VirtIODevice VirtIODevice;
>
>   typedef uint64_t pcibus_t;
>
> -void cpu_exec_init_all(unsigned long tb_size);
> +void tcg_exec_init(unsigned long tb_size);
> +bool tcg_enabled(void);
> +
> +void cpu_exec_init_all(void);
>
>   /* CPU save/load.  */
>   void cpu_save(QEMUFile *f, void *opaque);
> diff --git a/target-i386/helper.c b/target-i386/helper.c
> index 182009a..3332195 100644
> --- a/target-i386/helper.c
> +++ b/target-i386/helper.c
> @@ -1243,8 +1243,8 @@ CPUX86State *cpu_x86_init(const char *cpu_model)
>       cpu_exec_init(env);
>       env->cpu_model_str = cpu_model;
>
> -    /* init various static tables */
> -    if (!inited) {
> +    /* init various static tables used in TCG mode */
> +    if (tcg_enabled()&&  !inited) {
>           inited = 1;
>           optimize_flags_init();
>   #ifndef CONFIG_USER_ONLY
> diff --git a/target-ppc/helper.c b/target-ppc/helper.c
> index 176128a..e00b3e6 100644
> --- a/target-ppc/helper.c
> +++ b/target-ppc/helper.c
> @@ -3091,7 +3091,9 @@ CPUPPCState *cpu_ppc_init (const char *cpu_model)
>
>       env = qemu_mallocz(sizeof(CPUPPCState));
>       cpu_exec_init(env);
> -    ppc_translate_init();
> +    if (tcg_enabled()) {
> +        ppc_translate_init();
> +    }
>       env->cpu_model_str = cpu_model;
>       cpu_ppc_register_internal(env, def);
>
> diff --git a/target-s390x/helper.c b/target-s390x/helper.c
> index 1ce7079..443bb1d 100644
> --- a/target-s390x/helper.c
> +++ b/target-s390x/helper.c
> @@ -81,7 +81,7 @@ CPUS390XState *cpu_s390x_init(const char *cpu_model)
>
>       env = qemu_mallocz(sizeof(CPUS390XState));
>       cpu_exec_init(env);
> -    if (!inited) {
> +    if (tcg_enabled()&&  !inited) {
>           inited = 1;
>           s390x_translate_init();
>       }
> diff --git a/vl.c b/vl.c
> index 26bee4e..cc4998f 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -265,6 +265,7 @@ int kvm_allowed = 0;
>   int xen_allowed = 0;
>   uint32_t xen_domid;
>   enum xen_mode xen_mode = XEN_EMULATE;
> +static int tcg_tb_size;
>
>   static int default_serial = 1;
>   static int default_parallel = 1;
> @@ -1942,6 +1943,7 @@ static QEMUMachine *machine_parse(const char *name)
>
>   static int tcg_init(void)
>   {
> +    tcg_exec_init(tcg_tb_size * 1024 * 1024);
>       return 0;
>   }
>
> @@ -2102,7 +2104,6 @@ int main(int argc, char **argv, char **envp)
>       const char *loadvm = NULL;
>       QEMUMachine *machine;
>       const char *cpu_model;
> -    int tb_size;
>       const char *pid_file = NULL;
>       const char *incoming = NULL;
>   #ifdef CONFIG_VNC
> @@ -2142,7 +2143,6 @@ int main(int argc, char **argv, char **envp)
>       nb_numa_nodes = 0;
>       nb_nics = 0;
>
> -    tb_size = 0;
>       autostart= 1;
>
>       /* first pass of option parsing */
> @@ -2857,9 +2857,10 @@ int main(int argc, char **argv, char **envp)
>                   configure_rtc(opts);
>                   break;
>               case QEMU_OPTION_tb_size:
> -                tb_size = strtol(optarg, NULL, 0);
> -                if (tb_size<  0)
> -                    tb_size = 0;
> +                tcg_tb_size = strtol(optarg, NULL, 0);
> +                if (tcg_tb_size<  0) {
> +                    tcg_tb_size = 0;
> +                }
>                   break;
>               case QEMU_OPTION_icount:
>                   icount_option = optarg;
> @@ -3133,8 +3134,7 @@ int main(int argc, char **argv, char **envp)
>           }
>       }
>
> -    /* init the dynamic translator */
> -    cpu_exec_init_all(tb_size * 1024 * 1024);
> +    cpu_exec_init_all();
>
>       bdrv_init_with_whitelist();
>