backends/iommufd: Introduce the iommufd object

[mirror_qemu.git] / qemu-options.hx

diff --git a/qemu-options.hx b/qemu-options.hx
index 5b6d16ed58a049a33133aec08a7e7c076df677f2..5fe8ea57d2d2f9390a976ef2fefe86463e888bb1 100644 (file)
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3988,14 +3988,22 @@ ERST
 DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \
            "-initrd file    use 'file' as initial ram disk\n", QEMU_ARCH_ALL)
 SRST
+
 ``-initrd file``
     Use file as initial ram disk.
 
 ``-initrd "file1 arg=foo,file2"``
     This syntax is only available with multiboot.
 
-    Use file1 and file2 as modules and pass arg=foo as parameter to the
-    first module.
+    Use file1 and file2 as modules and pass ``arg=foo`` as parameter to the
+    first module. Commas can be provided in module parameters by doubling
+    them on the command line to escape them:
+
+``-initrd "bzImage earlyprintk=xen,,keep root=/dev/xvda1,initrd.img"``
+    Multiboot only. Use bzImage as the first module with
+    "``earlyprintk=xen,keep root=/dev/xvda1``" as its command line,
+    and initrd.img as the second module.
+
 ERST
 
 DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \
@@ -5216,6 +5224,18 @@ SRST
 
         The ``share`` boolean option is on by default with memfd.
 
+    ``-object iommufd,id=id[,fd=fd]``
+        Creates an iommufd backend which allows control of DMA mapping
+        through the ``/dev/iommu`` device.
+
+        The ``id`` parameter is a unique ID which frontends (such as
+        vfio-pci of vdpa) will use to connect with the iommufd backend.
+
+        The ``fd`` parameter is an optional pre-opened file descriptor
+        resulting from ``/dev/iommu`` opening. Usually the iommufd is shared
+        across all subsystems, bringing the benefit of centralized
+        reference counting.
+
     ``-object rng-builtin,id=id``
         Creates a random number generator backend which obtains entropy
         from QEMU builtin functions. The ``id`` parameter is a unique ID