On 14/03/2016 09:18, Ni, Ruiyu wrote:
> I tried to hook a software SMI (triggered by B2) but the handler/callback
> was never called.
>
> I know that when booting to ACPI OS, OS writes to B2 with certain value
> to tell firmware to enable SCI. That is achieved through the software SMI.
> The software SMI handler gets called when a certain value is written to B2.
> I am wondering how that is implemented in OVMF.
Because of the historical lack of SMI support in the firmware, this was
implemented directly in QEMU. In the case of Q35:
static void ich9_apm_ctrl_changed(uint32_t val, void *arg)
{
ICH9LPCState *lpc = arg;
/* ACPI specs 3.0, 4.7.2.5 */
acpi_pm1_cnt_update(&lpc->pm.acpi_regs,
val == ICH9_APM_ACPI_ENABLE,
val == ICH9_APM_ACPI_DISABLE);
if (val == ICH9_APM_ACPI_ENABLE || val == ICH9_APM_ACPI_DISABLE) {
return;
}
/* SMI_EN = PMBASE + 30. SMI control and enable register */
if (lpc->pm.smi_en & ICH9_PMIO_SMI_EN_APMC_EN) {
cpu_interrupt(current_cpu, CPU_INTERRUPT_SMI);
}
}
There are other parts of SMI support where QEMU is incomplete compared
to a real chipset, most notably EOS.
Paolo
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