The recently merged 228cf79376f1 ("ALSA: intel8x0: Improve performance
in virtual environment") is hacky and somewhat wrong.
First, the detection code
+ if (inside_vm < 0) {
+ /* detect KVM and Parallels virtual environments */
+ inside_vm = kvm_para_available();
+#if defined(__i386__) || defined(__x86_64__)
+ inside_vm = inside_vm ||
boot_cpu_has(X86_FEATURE_HYPERVISOR);
+#endif
+ }
+
is incorrect. It detects that you're running in a guest, but that
doesn't imply that the device you're accessing is emulated. It may be a
host device assigned to the guest; presumably the optimization you apply
doesn't work for real devices.
Second, the optimization itself looks fishy:
spin_lock(&chip->reg_lock);
do {
civ = igetbyte(chip, ichdev->reg_offset + ICH_REG_OFF_CIV);
ptr1 = igetword(chip, ichdev->reg_offset +
ichdev->roff_picb);
position = ichdev->position;
if (ptr1 == 0) {
udelay(10);
continue;
}
- if (civ == igetbyte(chip, ichdev->reg_offset +
ICH_REG_OFF_CIV) &&
- ptr1 == igetword(chip, ichdev->reg_offset +
ichdev->roff_picb))
+ if (civ != igetbyte(chip, ichdev->reg_offset +
ICH_REG_OFF_CIV))
+ continue;
+ if (chip->inside_vm)
+ break;
+ if (ptr1 == igetword(chip, ichdev->reg_offset +
ichdev->roff_picb))
break;
} while (timeout--);
Why is the emulated device timing out? Can't the emulation be fixed to
behave like real hardware?
Last, please copy kvm@xxxxxxxxxxxxxxx on such issues.
--
error compiling committee.c: too many arguments to function
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