Please explain what you're trying to do in detail. There should be no need to
ever do something like that.
Vlib_buffer_t's are embedded in private headroom space, tangent to the packet
DMA target [which starts at (struct mbuf *)mb->data_off].
Here's how we create the mempools:
rmp = rte_pktmbuf_pool_create ((char *) pool_name, /* pool name */
num_mbufs, /* number of mbufs */
512, /* cache size */
VLIB_BUFFER_HDR_SIZE, /* priv size */
VLIB_BUFFER_PRE_DATA_SIZE + VLIB_BUFFER_DATA_SIZE, /*
dataroom size */
socket_id); /* cpu socket */
As Chris wrote, b0->data is an array, not a pointer:
u8 data[0]; /**< Packet data. Hardware DMA here */
Thanks... Dave
From: vpp-dev-boun...@lists.fd.io [mailto:vpp-dev-boun...@lists.fd.io] On
Behalf Of Luke, Chris
Sent: Tuesday, February 28, 2017 7:15 AM
To: Li, Rujun <rujun...@intel.com>; vpp-dev@lists.fd.io
Subject: Re: [vpp-dev] wrong when i want to change vlib_buffer_t->data to my
pointer
Look at the definition of 'data' in the .h or in the docs:
https://docs.fd.io/vpp/17.04/dd/d10/structvlib__buffer__t.html
It's not a pointer, ergo you cannot do this. That is not how the buffer
mechanism works.
Chris.
From: vpp-dev-boun...@lists.fd.io<mailto:vpp-dev-boun...@lists.fd.io>
[mailto:vpp-dev-boun...@lists.fd.io] On Behalf Of Li, Rujun
Sent: Tuesday, February 28, 2017 3:44
To: vpp-dev@lists.fd.io<mailto:vpp-dev@lists.fd.io>
Subject: [vpp-dev] wrong when i want to change vlib_buffer_t->data to my pointer
Hi ,all
Now I am working on VPP and I met a problem. I have a pointer pointing to
packets receive from my changed DPDK and now I want to change
vlib_buffer_t->data to my pointer to avoid memory copy, but the errors were
reported that the vlib_buffer_t->data cannot be used as left value. My code
looks like:
Uint8_t * pktbuf;
//do assignment to pktbuf
Vlib_buffer_t * b = vlib_get_buffer(vm, tm->rx_buffers[i_rx]);
b->data = pktbuf;
and the error is : error: lvalue required as left operand of assignment
is there is something wrong with my code or vlib_buffer_t is projected from
assignment?
Best Wishes,
Rujun, Li
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