[dpdk-users] Segmentation fault in rte_eth_devices()

[dpdk-users] Segmentation fault in rte_eth_devices()

[David Aldrich]

Hi,

I am building an app based on dpdk-stable-18.11.8. I am seeing a
segmentation fault in my call to rte_eth_rx_burst(). I ran gdb on the core
dump and I see:

#0  0x0000000000f65680 in rte_eth_devices ()
#1  0x000000000048a03a in rte_eth_rx_burst (nb_pkts=7,
rx_pkts=0x7fab40620480, queue_id=0, port_id=<optimized out>)
    at
/opt/dpdk/dpdk-18.08/x86_64-native-linuxapp-gcc/include/rte_ethdev.h:3825
#2  Socket_poll (ucRxPortId=<optimized out>, ucRxQueId=ucRxQueId@entry=0
'\000', uiMaxNumOfRxFrm=uiMaxNumOfRxFrm@entry=7,
    pISocketListener=pISocketListener@entry=0xf635d0 <FH_gtFrontHaulObj+16>)
    at /data/<snip>/SocketClass.c:2188
#3  0x000000000048b941 in FH_perform (args_ptr=<optimized out>) at
/data/<snip>/FrontHaul.c:281
#4  0x00000000005788e4 in eal_thread_loop ()
#5  0x00007fab419fae65 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fab4172388d in clone () from /lib64/libc.so.6

So it seems that rte_eth_rx_burst() calls  rte_eth_devices () and that
function crashes, presumably because of an illegal memory access.

Please can anyone suggest a way of debugging this further to determine the
cause?

Re: [dpdk-users] Segmentation fault in rte_eth_devices()

[David Aldrich]

Following on from my question, I want to enable more debug info in DPDK.  I
am building DPDK using:

usertools/dpdk-setup.sh

Am I correct in thinking that the build commands in that script use make
and I should modify the appropriate:

config/defconfig_*

file (defconfig_x86_64-native-linuxapp-gcc in my case) ?

If so, would these values be appropriate?

CONFIG_ RTE_LIBRTE_ETHDEV_DEBUG=y
RTE_LOG_LEVEL=RTE_LOG_DEBUG
RTE_LIBRTE_ETHDEV_DEBUG=y

(not sure whether all values should be prefixed by 'CONFIG_'?)

Finally, where do I specify '-O0 -g' for the DPDK build?

Best regards
David

Re: [dpdk-users] Segmentation fault in rte_eth_devices()

[Vincent Li]

On Thu, 11 Jun 2020, David Aldrich wrote:

> Following on from my question, I want to enable more debug info in DPDK.  I
> am building DPDK using:
> 
> usertools/dpdk-setup.sh

When I use dpdk-setup.sh, after the first build, there is a target 
directory like x86_64-native-linuxapp-gcc created under dpdk root source 
directory, and there is '.config' file in x86_64-native-linuxapp-gcc 
directory, you can edit '.config' like 'CONFIG_RTE_LIBRTE_ETHDEV_DEBUG=y', 
then run dpdk-setup.sh again to build. this is one way to do it.

According to doc/build-sdk-quick.txt, you can also

make config T=x86_64-native-linuxapp-gcc

then manually edit x86_64-native-linuxapp-gcc/.config for your debug 
option


 > 
> Am I correct in thinking that the build commands in that script use make
> and I should modify the appropriate:
> 
> config/defconfig_*
> 
> file (defconfig_x86_64-native-linuxapp-gcc in my case) ?
> 
> If so, would these values be appropriate?
> 
> CONFIG_ RTE_LIBRTE_ETHDEV_DEBUG=y
> RTE_LOG_LEVEL=RTE_LOG_DEBUG
> RTE_LIBRTE_ETHDEV_DEBUG=y
> 
> (not sure whether all values should be prefixed by 'CONFIG_'?)
> 
> Finally, where do I specify '-O0 -g' for the DPDK build?

Again according to doc/build-sdk-quick.txt, maybe:

#EXTRA_CFLAGS='-O0 -g' make