t4vf_wr_mbox_core(9)

💌 NAME 💌

okay so this function is literally called t4vf_wr_mbox_core and it's giving "send a command to FW through the mailbox" energy. We're in the Kernel API Manual, bestie, and this is the tea. ☕✨

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✨ SYNOPSIS ✨

Here's the signature, exactly as it is, no cap:

int t4vf_wr_mbox_core (struct adapter *adapter , const void *cmd , int size , void *rpl , bool sleep_ok );

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🎀 ARGUMENTS 🎀

• adapter — the adapter itself, like the whole device vibe you're working with.
• cmd — the command to write, aka the actual thing you want FW to do.
• size — command length in bytes, so FW knows how much to read.
• rpl — where to optionally store the reply. If you want the reply, you put a pointer here; if not, it's NULL and you're just vibing.
• sleep_ok — if true, we may sleep while awaiting command completion. If false, no sleeping, we spin. Periodt.

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🦋 DESCRIPTION 🦋

So this function sends the given command to FW through the mailbox and then waits for FW to execute it. If rpl is not NULL, it's used to store FW's reply to the command. The command and its optional reply are the same length — that's important, no cap.

bestie, FW can take up to 500 ms to respond. That's half a second, so don't @ me if it's not instant. ⏳

sleep_ok determines whether we may sleep while awaiting the response. If sleeping is allowed, we use progressive backoff; otherwise we spin. So it's giving "respectful waiting" vs "anxious spinning" energy, iykyk.

The return value is 0 on success or a negative errno on failure. A failure can happen either because we're not able to execute the command at all, or because FW executes it but signals an error. In that second case, the return value is the error code indicated by FW — negated, so it comes back negative. Slay. 💅

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🌈 SEE ALSO 🌈

You should also check out the kernel file ./drivers/net/ethernet/chelsio/cxgb4vf/t4vf_hw.c (that's where the magic lives), plus all these other iconic functions: t4vf_record_mbox(9), fwcaps16_to_caps32(9), fwcap_to_fwspeed(9), t4vf_port_init(9), t4vf_fw_reset(9), t4vf_query_params(9), t4vf_set_params(9), t4vf_fl_pkt_align(9), t4vf_bar2_sge_qregs(9), t4vf_get_sge_params(9), t4vf_get_vpd_params(9), t4vf_get_dev_params(9), t4vf_get_rss_glb_config(9), t4vf_get_vfres(9), t4vf_read_rss_vi_config(9), t4vf_write_rss_vi_config(9), t4vf_config_rss_range(9), t4vf_alloc_vi(9), t4vf_free_vi(9), t4vf_enable_vi(9), t4vf_enable_pi(9), t4vf_identify_port(9), t4vf_set_rxmode(9), t4vf_alloc_mac_filt(9), t4vf_free_mac_filt(9), t4vf_change_mac(9), t4vf_set_addr_hash(9), t4vf_get_port_stats(9), t4vf_iq_free(9), t4vf_eth_eq_free(9), t4vf_link_down_rc_str(9), t4vf_handle_get_port_info(9), t4vf_update_port_info(9), t4vf_handle_fw_rpl(9), t4vf_get_vf_mac_acl(9), and t4vf_get_vf_vlan_acl(9). Obsessed with them all, fr fr. 🫶

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xoxo, your resident Unix bestie 💅 — this page is from the Kernel API Manual, dated October 2026, and the source file is ./drivers/net/ethernet/chelsio/cxgb4vf/t4vf_hw.c. Stay slay! 🦋🌸