That bit is documented in TLFS 5.0c as follows: Setting the polling bit will have the effect of unmasking an interrupt source, except that an actual interrupt is not generated. Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx> --- arch/x86/include/asm/hyperv-tlfs.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h index 5f10f7f2098d..92abc1e42bfc 100644 --- a/arch/x86/include/asm/hyperv-tlfs.h +++ b/arch/x86/include/asm/hyperv-tlfs.h @@ -809,7 +809,8 @@ union hv_synic_sint { u64 reserved1:8; u64 masked:1; u64 auto_eoi:1; - u64 reserved2:46; + u64 polling:1; + u64 reserved2:45; } __packed; }; -- 2.20.1