When using the Hyper-V Generation 2 hypervisor and trying to PXE boot a VM guest, the GRUB2 time functions are not working, which causes the PXE menu to display for a fraction of a second, instead of the usual 10 seconds or so, then boot the default menu entry, and immediately report that it timed out while loading the kernel. In other words, the time goes by superfast. For example, you'll get the message:
error: time out opening `rhel60x64/vmlinuz'.
This is because the functions in "./grub-core/kern/i386/tsc.c" that are used to calculate time are not working.
I found this site, which seems to say that the devices that GRUB2 uses to calculate the time have been removed from Hyper-V Generation 2:
Referring to changes made to Hyper-V Generation 2, it says:
Then we changed other devices such as removing the legacy i8042 keyboard controller (which has an interesting side effect I will talk about in a future part), PS/2 mouse, S3 Video, the Programmable Interrupt Controller (PIC), the Programmable Interrupt Timer (PIT), the Super I/O device on which floppy support relied. We actually went even further by removing the PCI bus as well. For good measure, we also removed the speaker and the numerical co-processor. We also revised ACPI.
I noticed that in "tsc.c", the grub_inb(GRUB_PIT_SPEAKER_PORT) call always returns 0xff on Hyper-V Generation 2.
grub_pit_wait (grub_uint16_t tics)
grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT)
& ~ (GRUB_PIT_SPK_DATA |
Is this a known issue that is already being addressed?