Re: [dpdk-dev] [PATCH 1/2] kdp: add kernel data path kernel module

[Ferruh Yigit <ferruh.yigit@intel.com>]

On Mon, Feb 08, 2016 at 05:14:54PM +0000, Reshma Pattan wrote:

Hi Reshma,

>
>
> On 1/27/2016 4:32 PM, Ferruh Yigit wrote:
>> This kernel module is based on KNI module, but this one is stripped
>> version of it and only for data messages, no control functionality
>> provided.
>>
>> FIFO implementation of the KNI is kept exact same, but ethtool related
>> code removed and virtual network management related code simplified.
>>
>> This module contains kernel support to create network devices and
>> this module has a simple driver for virtual network device, the driver
>> simply puts/gets packets to/from FIFO instead of real hardware.
>>
>> FIFO is created owned by userspace application, which is for this case
>> KDP PMD.
>>
>> In long term this patch intends to replace the KNI and KNI will be
>> depreciated.
>>
>> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
>> ---
>>   
>> diff --git a/lib/librte_eal/linuxapp/eal/include/exec-env/rte_kdp_common.h b/lib/librte_eal/linuxapp/eal/include/exec-env/rte_kdp_common.h
>> new file mode 100644
>> index 0000000..0c77f58
>> --- /dev/null
>> +++ b/lib/librte_eal/linuxapp/eal/include/exec-env/rte_kdp_common.h
>>
>> +/**
>> + * KDP name is part of memzone name.
>> + */
>> +#define RTE_KDP_NAMESIZE 32
>> +
>> +#ifndef RTE_CACHE_LINE_SIZE
>> +#define RTE_CACHE_LINE_SIZE 64       /**< Cache line size. */
>> +#endif
>
> Jerin Jacob has patch for cleaning of MACRO RTE_CACHE_LINE_SIZE and having 
> CONFIG_RTE_CACHE_LINE_SIZE
>
> in config file. You may need to remove this,once those changes are available 
> in code.
>
Thanks, when that patch applied, I can rebase code.
>> +
>> +/*
>> + * The kernel image of the rte_mbuf struct, with only the relevant fields.
>> + * Padding is necessary to assure the offsets of these fields
>> + */
>> +struct rte_kdp_mbuf {
>> +	void *buf_addr __attribute__((__aligned__(RTE_CACHE_LINE_SIZE)));
>> +	char pad0[10];
>> +
>> +	/**< Start address of data in segment buffer. */
>> +	uint16_t data_off;
>> +	char pad1[4];
>> +	uint64_t ol_flags;      /**< Offload features. */
>
>     You are not using ol_flags down in the code. Should this be removed?
>
Can't remove, this struct should match with rte_mbuf

>> +	char pad2[4];
>> +
>> +	/**< Total pkt len: sum of all segment data_len. */
>> +	uint32_t pkt_len;
>> +
>> +	/**< Amount of data in segment buffer. */
>> +	uint16_t data_len;
>> +
>> +	/* fields on second cache line */
>> +	char pad3[8] __attribute__((__aligned__(RTE_CACHE_LINE_SIZE)));
>> +	void *pool;
>> +	void *next;
>> +};
>> +
>
> Does all structures should have "__rte_cache_aligned" in their declarations? 
> Like other DPDK structs?
>
This is kernel module. Doesn't know about userspace library macros.
>
>> diff --git a/lib/librte_eal/linuxapp/kdp/kdp_dev.h b/lib/librte_eal/linuxapp/kdp/kdp_dev.h
>> new file mode 100644
>> index 0000000..52952b4
>> --- /dev/null
>> +++ b/lib/librte_eal/linuxapp/kdp/kdp_dev.h
>>
>> +
>> +#define KDP_ERR(args...) printk(KERN_DEBUG "KDP: Error: " args)
>> +#define KDP_PRINT(args...) printk(KERN_DEBUG "KDP: " args)
>> +
>> +#ifdef RTE_KDP_KO_DEBUG
>> +#define KDP_DBG(args...) printk(KERN_DEBUG "KDP: " args)
>
>     Is it good to haveKERN_DEBUG "KDP:Debug: " like Errors?
>
I think extra "Debug" prefix is not required here.

>
>> diff --git a/lib/librte_eal/linuxapp/kdp/kdp_fifo.h b/lib/librte_eal/linuxapp/kdp/kdp_fifo.h
>> new file mode 100644
>> index 0000000..a5fe080
>> --- /dev/null
>> +++ b/lib/librte_eal/linuxapp/kdp/kdp_fifo.h
>>
>> +/**
>> + * Adds num elements into the fifo. Return the number actually written
>> + */
>> +static inline unsigned
>> +kdp_fifo_put(struct rte_kdp_fifo *fifo, void **data, unsigned num)
>> +{
>> +	unsigned i = 0;
>> +	unsigned fifo_write = fifo->write;
>> +	unsigned fifo_read = fifo->read;
>> +	unsigned new_write = fifo_write;
>> +
>> +	for (i = 0; i < num; i++) {
>> +		new_write = (new_write + 1) & (fifo->len - 1);
>> +
>> +		if (new_write == fifo_read)
>> +			break;
>> +		fifo->buffer[fifo_write] = data[i];
>> +		fifo_write = new_write;
>> +	}
>> +	fifo->write = fifo_write;
>> +
>> +	return i;
>> +}
>
>     you can add header for all function declarations inside header file with 
> below format. Same for other header files and functions.
>
>     *@Description
>
>     *@params
>
>     *@Return value
>
This is private header.
>
>> diff --git a/lib/librte_eal/linuxapp/kdp/kdp_misc.c b/lib/librte_eal/linuxapp/kdp/kdp_misc.c
>> new file mode 100644
>> index 0000000..d97d1c0
>> --- /dev/null
>> +++ b/lib/librte_eal/linuxapp/kdp/kdp_misc.c
>> +static int
>> +kdp_compat_ioctl(struct inode *inode, unsigned int ioctl_num,
>> +		unsigned long ioctl_param)
>> +{
>> +	/* 32 bits app on 64 bits OS to be supported later */
>> +	KDP_PRINT("Not implemented.\n");
>
>     Should this be warning/ERR instead of PRINT?
>
>> diff --git a/lib/librte_eal/linuxapp/kdp/kdp_net.c b/lib/librte_eal/linuxapp/kdp/kdp_net.c
>> new file mode 100644
>> index 0000000..5c669f5
>> --- /dev/null
>> +++ b/lib/librte_eal/linuxapp/kdp/kdp_net.c
>> +
>> +static void
>> +kdp_net_set_rx_mode(struct net_device *dev)
>> +{
>> +}
>
>      Empty function body?
>
Yes, this is part of net_device_ops, and required to fake multicast support.

Regards,
ferruh