Re: [PATCH] IPMI: per-channel command registration

[Andrew Morton <akpm@osdl.org>]

On Mon, 25 Sep 2006 09:09:41 -0500
Corey Minyard <minyard@acm.org> wrote:

> 
> This patch adds the ability to register for a command per-channel in
> the IPMI driver.
> 
> If your BMC supports multiple channels, incoming messages can be
> differentiated by the channel on which they arrived. In this case it's
> useful to have the ability to register to receive commands on a
> specific channel instead the current behaviour of all channels.
> 
> +	case IPMICTL_REGISTER_FOR_CMD_CHANS:
> +	{
> +		struct ipmi_cmdspec_chans val;
> +
> +		if (copy_from_user(&val, arg, sizeof(val))) {

It becomes part of the ABI.

> +/*
> + * Register to get commands from other entities on specific channels.
> + * This way, you can only listen on specific channels, or have messages
> + * from some channels go to one place and other channels to someplace
> + * else.  The chans field is a bitmask, (1 << channel) for each channel.
> + * It may be IPMI_CHAN_ALL for all channels.
> + */
> +struct ipmi_cmdspec_chans
> +{
> +	unsigned char netfn;
> +	unsigned char cmd;
> +	unsigned int  chans;
> +};

Has it been tested with 32-bit userspace and a 64-bit kernel?

Even if it has, I'd be a bit worried that it depends upon the user's
compiler laying this structure out in the same manner as did his
kernel-provider's compiler.

Turning this into three u32's sounds safer?