Commit af5b9804 authored by Vivek Goyal's avatar Vivek Goyal Committed by Linus Torvalds
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[PATCH] x86_64: ioapic virtual wire mode fix

o Currently, during kexec reboot, IOAPIC is re-programmed back to virtual
  wire mode if there was an i8259 connected to it. This enables getting
  timer interrupts in second kernel in legacy mode.

o After putting into virtual wire mode, IOAPIC delivers the i8259 interrupts
  to CPU0. This works well for kexec but not for kdump as we might crash
  on a different CPU and second kernel will not see timer interrupts.

o This patch modifies the redirection table entry to deliver the timer
  interrupts to the cpu we are rebooting (instead of hardcoding to zero).
  This ensures that second kernel receives timer interrupts even on a
  non-boot cpu.

Signed-off-by: default avatarVivek Goyal <>
Signed-off-by: default avatarAndi Kleen <>
Signed-off-by: default avatarLinus Torvalds <>
parent 79f12614
......@@ -1307,7 +1307,8 @@ void disable_IO_APIC(void)
entry.dest_mode = 0; /* Physical */
entry.delivery_mode = dest_ExtINT; /* ExtInt */
entry.vector = 0;
entry.dest.physical.physical_dest = 0;
entry.dest.physical.physical_dest =
* Add it to the IO-APIC irq-routing table:
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