According to the TODO comment in hyperv_vmbus.h the value in macro MAX_NUM_CHANNELS_SUPPORTED should be configurable. The first patch accomplishes that by introducting uint max_num_channels_supported as module parameter. Also macro MAX_NUM_CHANNELS_SUPPORTED_DEFAULT is introduced with value 256, which is the currently used macro value. MAX_NUM_CHANNELS_SUPPORTED was found and replaced in two locations. During module initialization sanity checks are applied which will result in EINVAL or ERANGE if the given value is no multiple of 32 or larger than MAX_NUM_CHANNELS. While testing, we found a misleading typo in the comment for the macro MAX_NUM_CHANNELS which is fixed by the second patch. The third patch makes the added default macro configurable by introduction and use of Kconfig parameter HYPERV_VMBUS_DEFAULT_CHANNELS. Default value remains at 256. Two notes on these patches: 1) With above patches it is valid to configure max_num_channels_supported and MAX_NUM_CHANNELS_SUPPORTED_DEFAULT as 0. We simply don't know if that is a valid value. Doing so while testing still left us with a working Debian VM in Hyper-V on Windows 10. 2) To set the Kconfig parameter the user currently has to divide the desired default number of channels by 32 and enter the result of that calculation. This way both known constraints we got from the comments in the code are enforced. It feels a bit unintuitive though. We haven't found Kconfig options to ensure that the value is a multiple of 32. So if you'd like us to fix that we'd be happy for some input on how to settle it with Kconfig. Signed-off-by: Stefan Eschenbacher <stefan.eschenbacher@xxxxxx> Co-developed-by: Max Stolze <max.stolze@xxxxxx> Signed-off-by: Max Stolze <max.stolze@xxxxxx> Stefan Eschenbacher (3): drivers/hv: make max_num_channels_supported configurable drivers/hv: fix misleading typo in comment drivers/hv: add default number of vmbus channels to Kconfig drivers/hv/Kconfig | 13 +++++++++++++ drivers/hv/hyperv_vmbus.h | 8 ++++---- drivers/hv/vmbus_drv.c | 20 +++++++++++++++++++- 3 files changed, 36 insertions(+), 5 deletions(-) -- 2.20.1
