Re: [PATCH net-next v4 0/5] fbnic: Support larger RX pages

On Fri, Sep 25, 2026 at 12:44:07PM +0200, Björn Töpel wrote:

Hi!

This series adds support for large io_uring zero-copy RX buffers to
fbnic.

fbnic hardware consumes receive memory in 4 KiB device pages, while
io_uring may expose a larger software buffer, such as 256 KiB. Track
the device-page geometry per BDQ, represent each large buffer with
consecutive descriptors, and decode completions to the corresponding
offset within the buffer. HPQ keeps its existing PAGE_SIZE geometry.

Larger buffers also reduce pressure on the memory provider. One
provider allocation supplies multiple 4 KiB device pages, so the same
amount of receive memory needs fewer net_iov objects and fewer
allocation, refill, and recycle operations. Hardware descriptor use
remains unchanged.

Ring depth and buffer size must be validated together. An ethtool ring
change can otherwise make an active memory-provider configuration
invalid. Store RX ring depths in netdev_config, stage proposed values
in cfg_pending, and validate the default and each RX queue before
committing the change. Both netlink and ioctl use the same transaction
helpers.

The selftest requests a power-of-two buffer larger than twice the MTU,
checks the reported buffer length, and verifies received data. It does
not assume how packets are placed within the buffer.

This series depends on the fbnic real-queue synchronization fix:
https://lore.kernel.org/netdev/20260924191817.1843726-1-bjorn@kernel.org/ (local)

For the series:

Reviewed-by: Simon Horman <horms@kernel.org>