dwmac1000_v...e_mcast_bins(9)

💅 dwmac1000_v...e_mcast_bins(9) — like, the Kernel API Manual bestie ✨

okay so real talk, this is a page from the Kernel API Manual and it's about dwmac1000_validate_mcast_bins — yes the name is a whole mouthful, we're gonna get through it together 🫶

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🌸 NAME 🌸

dwmac1000_validate_mcast_bins — the little function whose entire job is checking that your Multicast filter bins count is, y'know, valid 💖

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✨ SYNOPSIS ✨

int dwmac1000_validate_mcast_bins (struct device *dev , int mcast_bins );

that's it. that's the whole vibe check. two args, one int coming back atcha 🔥

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🎀 ARGUMENTS 🎀

• dev — the struct device of the platform device, aka the main character we're validating stuff for 👑
• mcast_bins — the number of Multicast filtering bins, literally the number this whole function exists to judge 🙈

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🦋 DESCRIPTION 🦋

so what's actually going on here 👀 — this function validates the number of Multicast filtering bins that got specified by the configuration through the device tree.

and here's the tea ☕ the Synopsys GMAC is only down with 64 bins, 128 bins, or 256 bins. that's the whole guest list, no plus-ones 💅

"bins" btw refers to the division of CRC number space, which sounds scary but it's giving simple math tbh:

• 64 bins → that's 6 bits of the CRC
• 128 bins → that's 7 bits of the CRC
• 256 bins → that's 8 bits of the CRC

and literally any other setting? invalid 😭 and not in a cute way — it'll cause the filtering algorithm to fall back to Multicast promiscuous mode. so yeah, don't do that, fr fr 🙏

ngl, the vibe check here is strict on purpose — pick 64, 128, or 256 and you're slaying, pick anything else and promiscuous mode eats your day 💀

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🌈 SEE ALSO 🌈

the whole friend group 🫶 — go say hi:

• Kernel file ./drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
• dwmac1000_validate_ucast_entries(9)
• stmmac_axi_setup(9)
• stmmac_mtl_setup(9)
• stmmac_of_get_mdio(9)
• stmmac_mdio_setup(9)
• stmmac_of_get_mac_mode(9)
• stmmac_probe_config_dt(9)
• devm_stmmac_probe_config_dt(9)
• stmmac_pltfr_get_irq_array(9)
• stmmac_pltfr_init(9)
• stmmac_pltfr_exit(9)
• stmmac_pltfr_probe(9)
• devm_stmmac_pltfr_probe(9)
• stmmac_pltfr_remove(9)

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okay that's the page bestie, go forth and validate your bins 💜

mwah 💋 — this lil' slice of manpage magic came from ./drivers/net/ethernet/stmicro... and it's dated October 2026, and no I will not be taking questions about how it's from the future 💀✨