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Message Signaled Interrupts (MSI) are a method of signaling interrupts, using special in-band messages to replace traditional out-of-band signals on dedicated interrupt lines. While message signaled interrupts are more complex to implement in a device, they have some significant advantages over pin-based out-of-band interrupt signalling, such ...
The Message Signaled Interrupts (MSI) feature of the PCI 2.2 and later specifications cannot be used without the local APIC being enabled. [8] Use of MSI obviates the need for an I/O APIC. Additionally, up to 224 interrupts are supported in MSI mode, and IRQ sharing is not allowed. [9]
IRQ 9 – Advanced Configuration and Power Interface (ACPI) system control interrupt on Intel chipsets. [6] And/or left for the use of peripherals (use depends on OS) IRQ 10 – The interrupt is left for the use of peripherals (for example, SCSI or NIC) IRQ 11 – The interrupt is left for the use of peripherals (for example, SCSI or NIC)
Furthermore, on a modern x86 system, BIOS calls can only be performed in Real mode, or Virtual 8086 mode. v8086 is not an option in Long mode. This means that a modern operating system, which operates in Protected mode (32 bit), or Long mode (64 bit), would need to switch into real mode and back to call the BIOS - a hugely expensive operation.
A hardware interrupt is a condition related to the state of the hardware that may be signaled by an external hardware device, e.g., an interrupt request (IRQ) line on a PC, or detected by devices embedded in processor logic (e.g., the CPU timer in IBM System/370), to communicate that the device needs attention from the operating system (OS) [7] or, if there is no OS, from the bare metal ...
INT is an x86 instruction that triggers a software interrupt, and 13 hex is the interrupt number (as a hexadecimal value) being called. Modern computers come with both BIOS INT 13h and UEFI functionality that provides the same services and more, with the exception of UEFI Class 3 that completely removes CSM thus lacks INT 13h and other interrupts.
Modern systems use variants of the MSI protocol to reduce the amount of traffic in the coherency interconnect. The MESI protocol adds an "Exclusive" state to reduce the traffic caused by writes of blocks that only exist in one cache.
32-bit interrupt return. Differs from the older 16-bit IRET instruction in that it will pop interrupt return items (EIP,CS,EFLAGS; also ESP [j] and SS if there is a CPL change; and also ES,DS,FS,GS if returning to virtual 8086 mode) off the stack as 32-bit items instead of 16-bit items.