STM32 NI: fix linked-RX handling and robustness issues by HTRamsey · Pull Request #1317 · FreeRTOS/FreeRTOS-Plus-TCP

HTRamsey · 2026-02-25T06:48:38Z

Summary

This PR extracts the critical STM32 network-interface fixes from the broader work in #1309, so review can focus on correctness and stability first.

It specifically addresses the linked-RX/fragment handling concerns raised in review and keeps follow-on feature work out of scope.

Included changes

Rework HAL_ETH_RxLinkCallback handling for linked RX messages and fragmented frames
Remove obsolete ETH HAL workaround/warning code now superseded by current HAL
Remove outdated RX buffer length assert tied to legacy assumptions
Add missing packet filtering hook path and PHY link refresh helper
Use HAL getter APIs for state/error reporting where available
Add safety guards for ETH IRQ and RX allocation/cache handling paths
Refresh STM32 ETH HAL sources from upstream ST repos used by this tree

Out of scope (follow-up PRs)

Additional HAL feature enablement
Multiple NIC compatibility support

Copilot

Pull request overview

This PR extracts critical STM32 network interface fixes from PR #1309, focusing on correctness and stability improvements for linked-RX message handling, fragmented frame processing, and general robustness.

Changes:

Reworked linked RX message and fragmented frame handling with overflow protection and proper buffer management
Replaced direct HAL structure member access with HAL getter APIs (HAL_ETH_GetState, HAL_ETH_GetError, HAL_ETH_GetDMAError, HAL_ETH_GetMACError, HAL_ETH_GetTxBuffersNumber) for better encapsulation
Added missing packet filtering function eConsiderPacketForProcessing to handle protocol-level filtering when ipconfigETHERNET_DRIVER_FILTERS_PACKETS is enabled
Added vForceRefreshPhyLinkStatus helper and PHY link refresh on initialization complete
Added safety guard for ETH IRQ handler to check Instance != NULL before calling HAL_ETH_IRQHandler
Improved cache coherency handling in RX allocation and link callbacks with proper cache line alignment
Fixed RX descriptor index calculation to use previous index (ulPrevIdx) instead of current
Removed obsolete ETH HAL workarounds for bugs that are fixed in current HAL versions
Updated STM32 H7 and H5 ETH HAL extended driver files from upstream ST repositories (formatting changes only)

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
source/portable/NetworkInterface/STM32/NetworkInterface.c	Main network interface implementation with critical fixes for RX handling, HAL API usage, IRQ safety, and packet filtering
source/portable/NetworkInterface/STM32/Drivers/H7/stm32h7xx_hal_eth_ex.h	Updated H7 HAL extended header with formatting standardization from upstream ST
source/portable/NetworkInterface/STM32/Drivers/H7/stm32h7xx_hal_eth_ex.c	Updated H7 HAL extended source with formatting standardization from upstream ST
source/portable/NetworkInterface/STM32/Drivers/H5/stm32h5xx_hal_eth_ex.h	Updated H5 HAL extended header with formatting standardization from upstream ST
source/portable/NetworkInterface/STM32/Drivers/H5/stm32h5xx_hal_eth_ex.c	Updated H5 HAL extended source with formatting standardization from upstream ST

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Copilot · 2026-02-25T06:52:54Z

source/portable/NetworkInterface/STM32/Drivers/H7/stm32h7xx_hal_eth_ex.c

+    pVlanConfig->VLANTagControl = READ_BIT(heth->Instance->MACVIR, (ETH_MACVIR_VLP | ETH_MACVIR_VLC));
+  }
+
+  return HAL_OK;;


The extra semicolon after HAL_OK will cause a syntax error. This appears to be present in the upstream STMicroelectronics HAL source that was imported. Remove the extra semicolon.

Suggested change

return HAL_OK;;

return HAL_OK;

Copilot · 2026-02-25T06:52:54Z

source/portable/NetworkInterface/STM32/Drivers/H5/stm32h5xx_hal_eth_ex.c

+    pVlanConfig->VLANTagControl = READ_BIT(heth->Instance->MACVIR, (ETH_MACVIR_VLP | ETH_MACVIR_VLC));
+  }
+
+  return HAL_OK;;


The extra semicolon after HAL_OK will cause a syntax error. This appears to be present in the upstream STMicroelectronics HAL source that was imported. Remove the extra semicolon.

Suggested change

return HAL_OK;;

return HAL_OK;

source/portable/NetworkInterface/STM32/NetworkInterface.c

Consolidate the critical STM32 network-interface fixes into one change set for focused review. - Rework Rx link callback flow for linked RX messages and fragmented frame handling - Remove obsolete ETH HAL workarounds now covered by current ST HAL drivers - Add missing packet-filter hook integration and PHY link refresh helper - Use HAL getter APIs for state/error reporting instead of direct handle access - Add safety guards around ETH IRQ and RX allocation/cache maintenance paths Also refresh STM32 ETH HAL sources to current upstream ST driver versions used by this branch.

HTRamsey · 2026-02-25T10:16:45Z

@htibosch This has just fixes & HAL version updates now so should be easier to review

htibosch · 2026-02-26T10:30:51Z

Thank you very much, @HTRamsey.
I will test it on my NUCLEO-H755ZI-Q and report back.

htibosch · 2026-03-10T12:07:20Z

I had difficulties getting it to run on my STM32H755: it would start up, contact DHCP, send out logging on UDP, but there seems to be a problem on the reception side.
As a temporary fix I made it promiscuous:

xFilterConfig.ReceiveAllMode = ENABLE; // DISABLE;
xFilterConfig.PassAllMulticast = ENABLE; // DISABLE;
xFilterConfig.PromiscuousMode = ENABLE; // DISABLE;

and I changed these two functions to allow all packets:

static BaseType_t prvAcceptPacket( EMACData_t * pxEMACData,
                                   const NetworkBufferDescriptor_t * const pxDescriptor,
                                   uint16_t usLength )
{
    return pdTRUE;
}


static eFrameProcessingResult_t eConsiderPacketForProcessing( const uint8_t * const pucEthernetBuffer )
{
    return eProcessBuffer;
}

With these changes, all of my integration tests passed, like ARP, DHCP4, RA, ND, iperf3, NTP, DNS, ICMP/ping, TCP, UDP, HTTP/GET, all done both IPv4 and IPv6 (when available).

Now I will look at your list of proposed changes.

htibosch · 2026-03-10T12:30:54Z

When ipconfigUSE_LINKED_RX_MESSAGES is not enabled, the compiler gives an error. It can be solved safely with the following change:

-        pxTxPart = pxTxPart->pxNextBuffer;
+        #if ipconfigIS_ENABLED( ipconfigUSE_LINKED_RX_MESSAGES )
+            pxTxPart = pxTxPart->pxNextBuffer;
+        #else
+            pxTxPart = NULL;
+        #endif
     }

And I must admit that iperf will run faster without the linked-RX feature, both on IPv4 and IPv6 :-)

HTRamsey · 2026-03-10T18:10:52Z

I'll make some updates & do some more testing and get back to you

- Fix BroadcastFilter polarity (ENABLE blocks broadcasts, use DISABLE) - Add volatile to ISR/task shared variables (xSwitchRequired, xDropCurrentRxFrame) - NULL-terminate pxNextBuffer in linked-RX chain - Move prvValidateFrame (DMA error check) after HAL_ETH_ReadData where descriptor state is finalized - Init MAC filters/ARP offload before HAL_ETH_Start_IT - Flush TX metadata, semaphore, and HAL bookkeeping in prvRecoverFromCriticalError - Remove racy TX semaphore resync from prvReleaseTxPacket - Fix RxLinkCallback drop handler: don't clear xDropCurrentRxFrame prematurely, release start descriptor on multi-buffer overflow - Release TX buffer in TxFreeCallback on invalid uxDescCount - Remove premature RxAllocateCallback cache invalidation - Replace broken eConsiderPacketForProcessing with prvPassesPacketFilter covering IPv4/IPv6 checks the stack skips (fragmentation, loopback, version, broadcast source, multicast source, unspecified address) - Gate ipconfigETHERNET_DRIVER_FILTERS_PACKETS to H5/H7 with required checksum offload and frame-type filtering prerequisites - Fix uint8_t shift UB in MAC address helpers (cast to uint32_t) - Fix uint32_t to uintptr_t for register address arithmetic - Remove dead uxMACEntryIndex clamping, add slot reclaim on remove - Restore compatibility defines (ETH_IP_PAYLOAD_UNKNOWN/UDP/TCP/IGMP)

Copilot AI review requested due to automatic review settings February 25, 2026 06:48

Copilot started reviewing on behalf of HTRamsey February 25, 2026 06:49 View session

Copilot AI reviewed Feb 25, 2026

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HTRamsey force-pushed the fix/stm32-network-interface-important-fixes branch from becff5b to da1fd52 Compare February 25, 2026 08:29

HTRamsey force-pushed the fix/stm32-network-interface-important-fixes branch from da1fd52 to 490635a Compare February 25, 2026 10:03

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STM32 NI: fix linked-RX handling and robustness issues#1317

STM32 NI: fix linked-RX handling and robustness issues#1317
HTRamsey wants to merge 2 commits intoFreeRTOS:mainfrom
HTRamsey:fix/stm32-network-interface-important-fixes

HTRamsey commented Feb 25, 2026 •

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Summary

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Out of scope (follow-up PRs)

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HTRamsey commented Feb 25, 2026 •

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