kernel 如何调用uefi的runtime service

来源：互联网发布：集团管控软件编辑：程序博客网时间：2024/06/05 03:35

在drivers/firmware/efi/runtime-wrappers.c 中会建立kernel调用uefi的runtime service
static int __init arm64_enable_runtime_services(void)
{

   /* Set up runtime services function pointers */
   efi_native_runtime_setup();
   set_bit(EFI_RUNTIME_SERVICES, &efi.flags);

}
early_initcall(arm64_enable_runtime_services);
可见是通过early_initcall自动调用arm64_enable_runtime_services
void efi_native_runtime_setup(void)
{
   efi.get_time = virt_efi_get_time;
   efi.set_time = virt_efi_set_time;
   efi.get_wakeup_time = virt_efi_get_wakeup_time;
   efi.set_wakeup_time = virt_efi_set_wakeup_time;
   efi.get_variable = virt_efi_get_variable;
   efi.get_next_variable = virt_efi_get_next_variable;

}
我们以virt_efi_get_time为例
static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
{
   unsigned long flags;
   efi_status_t status;

   spin_lock_irqsave(&rtc_lock, flags);
   spin_lock(&efi_runtime_lock);
   status = efi_call_virt(get_time, tm, tc);
   spin_unlock(&efi_runtime_lock);
   spin_unlock_irqrestore(&rtc_lock, flags);
   return status;
}
efi_call_virt 定义如下：
#define efi_call_virt(f, ...)                       \
({                                   \
   efi_##f##_t *__f;                       \
   efi_status_t __s;                       \
                                   \
   kernel_neon_begin();                       \
   efi_virtmap_load();                       \
   __f = efi.systab->runtime->f;                   \
   __s = __f(__VA_ARGS__);                       \
   efi_virtmap_unload();                       \
   kernel_neon_end();                       \
   __s;                               \
})

替换掉宏定义最终还是调用efi.systab->runtime->get_time(tm,tc)

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