Hi,
To test this, I’m running the [PRU_RPMsg_Echo_Interrupt0] on the pru0 which take the text I send to it and send it back to me.
What I’m testing is sending and receiving message on the arm side. My problem is when using the linux read function in c. I ask to read let say 10 character but it sends me back the whole rpmsg_pru30 buffer.
This can cause buffer overflow. Does someone know the solution ?
Here is my code on the arm side:
/*
* Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com/
*
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* * Neither the name of Texas Instruments Incorporated nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/poll.h>
#define MAX_BUFFER_SIZE 512
char readBuf[MAX_BUFFER_SIZE];
#define NUM_MESSAGES 100
#define DEVICE_NAME "/dev/rpmsg_pru30"
// declare fcntl flag variable
int fcntl_flags;
int main(void)
{
struct pollfd pollfds[1];
int i;
int result = 0;
/* Open the rpmsg_pru character device file */
pollfds[0].fd = open(DEVICE_NAME, O_RDWR);
/*
* If the RPMsg channel doesn't exist yet the character device
* won't either.
* Make sure the PRU firmware is loaded and that the rpmsg_pru
* module is inserted.
*/
if (pollfds[0].fd < 0) {
printf("Failed to open %s\n", DEVICE_NAME);
return -1;
}
fcntl_flags = fcntl(pollfds[0].fd,F_GETFL,0); // get the current flag settings
fcntl(pollfds[0].fd,F_SETFL, fcntl_flags | O_NONBLOCK); // set the non-blocking bit in the flags
/* The RPMsg channel exists and the character device is opened */
printf("Opened %s, sending %d messages\n\n", DEVICE_NAME, NUM_MESSAGES);
for (i = 0; i < NUM_MESSAGES; i++) {
/* Send 'hello world!' to the PRU through the RPMsg channel */
result = write(pollfds[0].fd, "hello world!", 13);
if (result > 0)
printf("Message %d: Sent to PRU\n", i);
/* Poll until we receive a message from the PRU and then print it */
result = read(pollfds[0].fd, readBuf, 5);
if (result > 0)
printf("5 char only:%s\n", readBuf);
result = read(pollfds[0].fd, readBuf, MAX_BUFFER_SIZE);
if (result > 0)
printf("Message %d received from PRU:%s\n\n", i, readBuf);
}
/* Received all the messages the example is complete */
printf("Received %d messages, closing %s\n", NUM_MESSAGES, DEVICE_NAME);
/* Close the rpmsg_pru character device file */
close(pollfds[0].fd);
return 0;
}
It was copied from the Ti lab5 and I only added a second read with a limited number of char readed
result = read(pollfds[0].fd, readBuf, 5);
if (result > 0)
printf("5 char only:%s\n", readBuf);
Here is my beaglebone black version.sh :
git:/opt/scripts/:[b39ec679648a6be8f25f48bd1c9784c1fc5a0c46]
eeprom:[A335BNLT00C02151SBB38709]
model:[TI_AM335x_BeagleBone_Black]
dogtag:[BeagleBoard.org Debian Buster IoT Image 2020-04-06]
bootloader:[eMMC-(default)]:[/dev/mmcblk1]:[U-Boot 2019.04-00002-g31a8ae0206]:[location: dd MBR]
UBOOT: Booted Device-Tree:[am335x-boneblack-uboot-univ.dts]
UBOOT: Loaded Overlay:[AM335X-PRU-RPROC-4-19-TI-00A0]
UBOOT: Loaded Overlay:[BB-ADC-00A0]
UBOOT: Loaded Overlay:[BB-BONE-eMMC1-01-00A0]
UBOOT: Loaded Overlay:[BB-NHDMI-TDA998x-00A0]
kernel:[4.19.94-ti-r42]
nodejs:[v10.15.2]
/boot/uEnv.txt Settings:
uboot_overlay_options:[enable_uboot_overlays=1]
uboot_overlay_options:[disable_uboot_overlay_audio=1]
uboot_overlay_options:[uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-19-TI-00A0.dtbo]
uboot_overlay_options:[enable_uboot_cape_universal=1]
pkg check: to individually upgrade run: [sudo apt install --only-upgrade <pkg>]
pkg:[bb-cape-overlays]:[4.14.20200403.0-0rcnee0~buster+20200403]
pkg:[bb-wl18xx-firmware]:[1.20200322.0-0rcnee0~buster+20200322]
pkg:[kmod]:[26-1]
pkg:[librobotcontrol]:[1.0.4-git20190227.1-0rcnee0~buster+20190327]
pkg:[firmware-ti-connectivity]:[20190717-2rcnee1~buster+20200305]
groups:[debian : debian adm kmem dialout cdrom floppy audio dip video plugdev users systemd-journal bluetooth netdev i2c gpio pwm eqep remoteproc admin spi iio docker tisdk weston-launch xenomai cloud9ide]
cmdline:[console=ttyO0,115200n8 bone_capemgr.uboot_capemgr_enabled=1 root=/dev/mmcblk1p1 ro rootfstype=ext4 rootwait coherent_pool=1M net.ifnames=0 lpj=1990656 rng_core.default_quality=100 quiet]
dmesg | grep remote
[ 68.497411] remoteproc remoteproc0: wkup_m3 is available
[ 68.639781] remoteproc remoteproc0: powering up wkup_m3
[ 68.639815] remoteproc remoteproc0: Booting fw image am335x-pm-firmware.elf, size 217168
[ 68.640106] remoteproc remoteproc0: remote processor wkup_m3 is now up
[ 72.039783] remoteproc remoteproc1: 4a334000.pru is available
[ 72.042141] remoteproc remoteproc2: 4a338000.pru is available
dmesg | grep pru
[ 72.039783] remoteproc remoteproc1: 4a334000.pru is available
[ 72.039992] pru-rproc 4a334000.pru: PRU rproc node pru@4a334000 probed successfully
[ 72.042141] remoteproc remoteproc2: 4a338000.pru is available
[ 72.042319] pru-rproc 4a338000.pru: PRU rproc node pru@4a338000 probed successfully
dmesg | grep pinctrl-single
[ 0.917251] pinctrl-single 44e10800.pinmux: 142 pins, size 568
dmesg | grep gpio-of-helper
[ 0.930470] gpio-of-helper ocp:cape-universal: ready
lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
END
Also I have tested python open and c fopen which both don’t have this issue but no matter what, they block when reading the EOF and it is NOT ACCEPTABLE for my application.
Thanks for the help.