Messages in this thread |  | | Date | Tue, 9 Feb 2021 09:24:07 +0800 | From | Shuo A Liu <> | Subject | Re: [PATCH v9 01/18] docs: acrn: Introduce ACRN |
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Hi Randy,
On Mon 8.Feb'21 at 11:48:07 -0800, Randy Dunlap wrote: >On 2/6/21 7:10 PM, shuo.a.liu@intel.com wrote: >> From: Shuo Liu <shuo.a.liu@intel.com> >> >> Add documentation on the following aspects of ACRN: >> >> 1) A brief introduction on the architecture of ACRN. >> 2) I/O request handling in ACRN. >> 3) CPUID functions of ACRN. > >> --- > >> diff --git a/Documentation/virt/acrn/io-request.rst b/Documentation/virt/acrn/io-request.rst >> new file mode 100644 >> index 000000000000..6cc3ea0fa1f5 >> --- /dev/null >> +++ b/Documentation/virt/acrn/io-request.rst >> @@ -0,0 +1,97 @@ >> +.. SPDX-License-Identifier: GPL-2.0 >> + >> +I/O request handling >> +==================== >> + >... >> + >> +1. I/O request >> +-------------- >> + >> +For each User VM, there is a shared 4-KByte memory region used for I/O requests >> +communication between the hypervisor and Service VM. An I/O request is a >> +256-byte structure buffer, which is 'struct acrn_io_request', that is filled by >> +an I/O handler of the hypervisor when a trapped I/O access happens in a User >> +VM. ACRN userspace in the Service VM first allocates a 4-KByte page and passes >> +the GPA (Guest Physical Address) of the buffer to the hypervisor. The buffer is >> +used as an array of 16 I/O request slots with each I/O request slot being 256 >> +bytes. This array is indexed by vCPU ID. > >Does this mean that ACRN has a limit of 16 vCPUs ?
Yes. Now it is a limitation.
Thanks shuo
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