Re: [Qemu-devel] [PULL 22/55] q35: ioapic: add support for emulated IOAPIC IR

[Emilio G. Cota]

On Tue, Jul 19, 2016 at 01:44:41 +0300, Michael S. Tsirkin wrote:
> From: Peter Xu <address@hidden>
> 
> This patch translates all IOAPIC interrupts into MSI ones. One pseudo
> ioapic address space is added to transfer the MSI message. By default,
> it will be system memory address space. When IR is enabled, it will be
> IOMMU address space.
> 
> Currently, only emulated IOAPIC is supported.
> 
> Idea suggested by Jan Kiszka and Rita Sinha in the following patch:
> 
> https://lists.gnu.org/archive/html/qemu-devel/2016-03/msg01933.html
> 
> Signed-off-by: Peter Xu <address@hidden>
> Signed-off-by: Peter Xu <address@hidden>
> ---
>  include/hw/i386/apic-msidef.h     |  1 +
>  include/hw/i386/ioapic_internal.h |  1 +
>  include/hw/i386/pc.h              |  4 ++++
>  hw/i386/intel_iommu.c             |  6 +++++-
>  hw/i386/pc.c                      |  3 +++
>  hw/intc/ioapic.c                  | 28 ++++++++++++++++++++++++----
>  6 files changed, 38 insertions(+), 5 deletions(-)

This commit (which sits between 2.6 and 2.7) doesn't let me boot a
buildroot-generated x86_64 image when QEMU is configured with
--with-coroutine=gthread (it deadlocks on the BQL shortly after
the framebuffer comes up.)

Is this something we should worry about? I see in the configure
script that --with-coroutine=gthread "is not functional enough to run
QEMU proper". My goal is to use thread sanitizer (tsan) to test
mttcg for x86-64. Unfortunately, tsan blows with ucontext coroutines.

Thanks,

                Emilio