STM32H745: unable to open 2 sockets at the same time

[joelguittet]

Hello community !

I'm writing an application that need to open multiple sockets at the same time. I'm using nucleo_h745zi_q_m7 evaluation board with Ethernet interface.

One sockets is fine (http client connecting to a server using TLS, port 443), but then I'm not able to open a new socket. I need to close the first one and wait a bit to permit a second socket to be used.

I don't know at all which settings I should modify, I have already checked at the menuconfig but don't find anything related to this in the Networking or STM32 Ethernet Driver sections.

Thanks for any ideas that may help!

Joel

[jukkar]

Please check the values of following options

CONFIG_NET_MAX_CONTEXTS
CONFIG_NET_MAX_CONN
CONFIG_POSIX_MAX_FDS
CONFIG_NET_SOCKETS_POLL_MAX

The issue is probably related to one of those options to be too small. Note that one TLS connection uses two sockets so you might hit a limit. I suspect the CONFIG_NET_SOCKETS_POLL_MAX as I saw similar issue yesterday (default value is 3).

[joelguittet]

Thanks @jukkar for the quick answer to this topic!

All these values were the default, so:

• I have increased CONFIG_NET_SOCKETS_POLL_MAX to 10 => No changes
• I have increased all of them x4 => No changes

Just to give more details about this, I added an errno log, and the exact error is socket() returns -1 with errno 12 (no memory). So I guess the idea is not bad but probably another settings should be changed.

Joel

[joelguittet]

Following reading #38191 I have also increased the followings:

CONFIG_NET_BUF_RX_COUNT=64
CONFIG_NET_BUF_TX_COUNT=64
CONFIG_NET_PKT_RX_COUNT=32
CONFIG_NET_PKT_TX_COUNT=32

But still no progress so far :-(

[jukkar]

Hmm, perhaps this is related to TLS. Can you try without TLS, do you get the same result?

[joelguittet]

Except making a specific application, I'm not able to do it, the distant server is only accepting HTTPS.

[jukkar]

The socket() returning ENOMEM indicates that some limit is too small. And for TLS sockets it might be caused some mbedtls config option and there are many of those.

[joelguittet]

Yeah I know particularly about the heap size, configured 60000 Bytes (I hope it's enough!). I have set the following to be exact:

CONFIG_MBEDTLS=y
CONFIG_MBEDTLS_BUILTIN=y
CONFIG_MBEDTLS_ENABLE_HEAP=y
CONFIG_MBEDTLS_HEAP_SIZE=60000
CONFIG_MBEDTLS_CFG_FILE="config-tls-generic.h"
CONFIG_MBEDTLS_ECDH_C=y
CONFIG_MBEDTLS_ECDSA_C=y
CONFIG_MBEDTLS_ECP_C=y
CONFIG_MBEDTLS_ECP_DP_SECP256R1_ENABLED=y
CONFIG_MBEDTLS_GENPRIME_ENABLED=y
CONFIG_MBEDTLS_CIPHER_AES_ENABLED=y
CONFIG_MBEDTLS_CIPHER_CCM_ENABLED=y
CONFIG_MBEDTLS_CIPHER_GCM_ENABLED=y
CONFIG_MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED=y
CONFIG_MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED=y
CONFIG_MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED=y
CONFIG_MBEDTLS_KEY_EXCHANGE_RSA_ENABLED=y
CONFIG_MBEDTLS_PEM_CERTIFICATE_FORMAT=y
CONFIG_MBEDTLS_PK_WRITE_C=y
CONFIG_MBEDTLS_ZEPHYR_ENTROPY=y
CONFIG_MBEDTLS_SSL_MAX_CONTENT_LEN=16384
CONFIG_MBEDTLS_SERVER_NAME_INDICATION=y

[joelguittet]

@jukkar maybe you know is there a good tutorial somewhere to perform debugging ? I mean something official supported by Zephyr. If i go step by step probably I can catch the error when this occurs. I found several vscode information but plenty of them outdated or too much specific, not succeed to use it properly :(

[joelguittet]

@jukkar I just increased CONFIG_MBEDTLS_HEAP_SIZE=100000 (with no real hope this can fix the issue to be honest), and it's now working properly ! i have also set CONFIG_POSIX_MAX_FDS=16.

By the way, 100000 looks very large and 60000 was already very large. Any advice to configure this ? I will check in parallel other topics about this setting, I need more documentation about that, if no information found I will open anew discussion.

[jukkar]

Agreed, the memory amount sounds excessive. I just recently had similar kind of issues with TLS, the connection establishment was failing. It required me adding prints all over the TLS code path to see where ENOMEM was returned. It did not took too long time and in my case the culprit was the CONFIG_NET_SOCKETS_POLL_MAX=3 which only allowed one TLS connection establishement at a time.
I try to do the debugging in native_sim board as then Zephyr is just a process in my Linux host and it makes investigation easier (at least for networking issues).