Re: [patch 25/29] xen: Add the Xen virtual network device driver.

Jeremy Fitzhardinge
2007-05-07T21:11:47Z

Christoph Hellwig wrote:
> On Fri, May 04, 2007 at 04:21:16PM -0700, Jeremy Fitzhardinge wrote:
>
>> +/*
>> + * Mutually-exclusive module options to select receive data path:
>> + * rx_copy : Packets are copied by network backend into local memory
>> + * rx_flip : Page containing packet data is transferred to our ownership
>> + * For fully-virtualised guests there is no option - copying must be used.
>> + * For paravirtualised guests, flipping is the default.
>> + */
>> +static enum {
>> + RX_COPY = 0,
>> + RX_FLIP = 1,
>> +} rx_mode = RX_FLIP;
>> +MODULE_PARM_DESC(rx_mode, "How to get packets from card: 0->copy, 1->flip");
>>
>
> There only seems to be a module description but no actual paramter for
> this. I wish people would have listened to me back then and made the
> description part of the modular_param statement..

Is this correct?

---
drivers/net/xen-netfront.c | 32 ++++++++++++++++++++++++++++----
1 file changed, 28 insertions(+), 4 deletions(-)

===================================================================
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -62,16 +62,40 @@ struct netfront_cb {

/*
* Mutually-exclusive module options to select receive data path:
- * rx_copy : Packets are copied by network backend into local memory
- * rx_flip : Page containing packet data is transferred to our ownership
+ * copy : Packets are copied by network backend into local memory
+ * flip : Page containing packet data is transferred to our ownership
* For fully-virtualised guests there is no option - copying must be used.
* For paravirtualised guests, flipping is the default.
*/
-static enum {
+static enum rx_mode {
RX_COPY = 0,
RX_FLIP = 1,
} rx_mode = RX_FLIP;
-MODULE_PARM_DESC(rx_mode, "How to get packets from card: 0->copy, 1->flip");
+MODULE_PARM_DESC(rx_mode, "How to get packets from card: \"copy\" or \"flip\"");
+
+static int set_rx_mode(const char *val, struct kernel_param *kp)
+{
+ enum rx_mode *rxmp = kp->arg;
+ int ret = 0;
+
+ if (strcmp(val, "copy") == 0)
+ *rxmp = RX_COPY;
+ else if (strcmp(val, "flip") == 0)
+ *rxmp = RX_FLIP;
+ else
+ ret = -EINVAL;
+
+ return ret;
+}
+
+static int get_rx_mode(char *buffer, struct kernel_param *kp)
+{
+ enum rx_mode *rxmp = kp->arg;
+
+ return sprintf(buffer, "%s", *rxmp == RX_COPY ? "copy" : "flip");
+}
+
+module_param_call(rx_mode, set_rx_mode, get_rx_mode, &rx_mode, 0400);

#define RX_COPY_THRESHOLD 256