On Tue, Jan 23, 2024 at 10:13:52AM +0000, Chen, Jiqian wrote: > On 2024/1/23 07:37, Bjorn Helgaas wrote: > > On Fri, Jan 05, 2024 at 02:22:17PM +0800, Jiqian Chen wrote: > >> There is a need for some scenarios to use gsi sysfs. > >> For example, when xen passthrough a device to dumU, it will > >> use gsi to map pirq, but currently userspace can't get gsi > >> number. > >> So, add gsi sysfs for that and for other potential scenarios. > ... > > I don't know enough about Xen to know why it needs the GSI in > > userspace. Is this passthrough brand new functionality that can't be > > done today because we don't expose the GSI yet? > > In Xen architecture, there is a privileged domain named Dom0 that > has ACPI support and is responsible for detecting and controlling > the hardware, also it performs privileged operations such as the > creation of normal (unprivileged) domains DomUs. When we give to a > DomU direct access to a device, we need also to route the physical > interrupts to the DomU. In order to do so Xen needs to setup and map > the interrupts appropriately. What kernel interfaces are used for this setup and mapping?
