Re: [PATCH v2] misc: pvpanic: introduce device capability

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Jan 08, 2021 at 07:17:10PM +0800, zhenwei pi wrote:
> According to pvpanic spec:
> https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/specs/pvpanic.txt
> 
> The guest should determine pvpanic capability by RDPT, so initialize
> capability during device probing. There is no need to register panic
> notifier callback function if no events supported.
> 
> Before sending event to host side, check capability firstly.
> Suggested by Paolo, export capability of pvpanic device by read-only
> module parameter.
> 
> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
> ---
>  drivers/misc/pvpanic.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/misc/pvpanic.c b/drivers/misc/pvpanic.c
> index 951b37da5e3c..c55a9d2fd001 100644
> --- a/drivers/misc/pvpanic.c
> +++ b/drivers/misc/pvpanic.c
> @@ -19,6 +19,9 @@
>  #include <uapi/misc/pvpanic.h>
>  
>  static void __iomem *base;
> +static unsigned int capability = PVPANIC_PANICKED | PVPANIC_CRASH_LOADED;
> +module_param(capability, uint, 0444);
> +MODULE_PARM_DESC(capability, "capability of pvpanic device");

This is not the 1990's, please do not add new module parameters :(

Use sysfs, and properly document the file in Documentation/ABI/

thanks,

greg k-h