Currently host page cache setting for a block device cannot be changed without restarting a running VM. Following patchset [V3] is for enabling dynamic change of hostcache setting for block devices through qemu monitor and QMP. Code changes are based on patches from Christoph Hellwig and Prerna Saxena.
Changes from patchset V2: 1. Command "block_set" added for changing block device params dynamically 2. Enhanced info-block to display hostcache setting of block device 3. Added qmp interfaces for setting and querying hostcache New block command added: "block_set" -- Sets block device parameters while guest is running. Usage: block_set <device> <param> <value> <device> = block device <param> = parameter (say, "hostcache") <value> = on/off 1/3 Enhance "info block" to display hostcache setting 2/3 New error classes for file reopen and device insertion 3/3 Command "block_set" for dynamic params change for block device qemu/block.c | 62 +++++++++++++++++++++++++++++++++++++++++ +++++++++---- qemu/block.h | 2 ++ qemu/blockdev.c | 32 ++++++++++++++++++++++++++++++++ qemu/blockdev.h | 1 + qemu/hmp-commands.hx | 15 +++++++++++++++ qemu/qerror.c | 8 ++++++++ qemu/qerror.h | 6 ++++++ qemu/qmp-commands.hx | 2 ++ qmp-commands.hx | 30 +++++++++++++++++++++++++++++- 9 files changed, 153 insertions(+), 5 deletions(-) ~ ~ ~ ~