We added more generic options after introducing -blockdev and forgot to
update the documentation (man page and --help output) accordingly. Do
that now.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qemu-options.hx | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/qemu-options.hx b/qemu-options.hx
index 793d70ff93..2e6ba5ef1f 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -849,7 +849,8 @@ ETEXI
DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
"-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n"
" [,cache.direct=on|off][,cache.no-flush=on|off]\n"
- " [,read-only=on|off][,detect-zeroes=on|off|unmap]\n"
+ " [,read-only=on|off][,auto-read-only=on|off]\n"
+ " [,force-share=on|off][,detect-zeroes=on|off|unmap]\n"
" [,driver specific parameters...]\n"
" configure a block backend\n", QEMU_ARCH_ALL)
STEXI
@@ -885,6 +886,25 @@ name is not intended to be predictable and changes between QEMU invocations.
For the top level, an explicit node name must be specified.
@item read-only
Open the node read-only. Guest write attempts will fail.
+
+Note that some block drivers support only read-only access, either generally or
+in certain configurations. In this case, the default value
+@option{read-only=off} does not work and the option must be specified
+explicitly.
+@item auto-read-only
+If @option{auto-read-only=on} is set, QEMU may fall back to read-only usage
+even when @option{read-only=off} is requested, or even switch between modes as
+needed, e.g. depending on whether the image file is writable or whether a
+writing user is attached to the node.
+@item force-share
+Override the image locking system of QEMU by forcing the node to utilize
+weaker shared access for permissions where it would normally request exclusive
+access. When there is the potential for multiple instances to have the same
+file open (whether this invocation of qemu is the first or the second
+instance), both instances must permit shared access for the second instance to
+succeed at opening the file.
+
+Enabling @option{force-share=on} requires @option{read-only=on}.
@item cache.direct
The host page cache can be avoided with @option{cache.direct=on}. This will
attempt to do disk IO directly to the guest's memory. QEMU may still perform an
--
2.20.1
On Fri, 18 Oct 2019 at 13:02, Kevin Wolf <kwolf@redhat.com> wrote: > > We added more generic options after introducing -blockdev and forgot to > update the documentation (man page and --help output) accordingly. Do > that now. > > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > --- > qemu-options.hx | 22 +++++++++++++++++++++- > 1 file changed, 21 insertions(+), 1 deletion(-) > > diff --git a/qemu-options.hx b/qemu-options.hx > index 793d70ff93..2e6ba5ef1f 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -849,7 +849,8 @@ ETEXI > DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev, > "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n" > " [,cache.direct=on|off][,cache.no-flush=on|off]\n" > - " [,read-only=on|off][,detect-zeroes=on|off|unmap]\n" > + " [,read-only=on|off][,auto-read-only=on|off]\n" > + " [,force-share=on|off][,detect-zeroes=on|off|unmap]\n" > " [,driver specific parameters...]\n" > " configure a block backend\n", QEMU_ARCH_ALL) > STEXI > @@ -885,6 +886,25 @@ name is not intended to be predictable and changes between QEMU invocations. > For the top level, an explicit node name must be specified. > @item read-only > Open the node read-only. Guest write attempts will fail. > + > +Note that some block drivers support only read-only access, either generally or > +in certain configurations. In this case, the default value > +@option{read-only=off} does not work and the option must be specified > +explicitly. > +@item auto-read-only > +If @option{auto-read-only=on} is set, QEMU may fall back to read-only usage > +even when @option{read-only=off} is requested, or even switch between modes as > +needed, e.g. depending on whether the image file is writable or whether a > +writing user is attached to the node. > +@item force-share > +Override the image locking system of QEMU by forcing the node to utilize > +weaker shared access for permissions where it would normally request exclusive > +access. When there is the potential for multiple instances to have the same > +file open (whether this invocation of qemu is the first or the second "QEMU" should be all-upper-case. > +instance), both instances must permit shared access for the second instance to > +succeed at opening the file. > + > +Enabling @option{force-share=on} requires @option{read-only=on}. > @item cache.direct > The host page cache can be avoided with @option{cache.direct=on}. This will > attempt to do disk IO directly to the guest's memory. QEMU may still perform an > -- > 2.20.1 Otherwise Reviewed-by: Peter Maydell <peter.maydell@linaro.org> thanks -- PMM
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