epf_ntb_peer_spad_bar_set(9)

💅 epf_ntb_peer_spad_bar_set 💅

okay so real quick, bestie — this is a page from the Kernel API Manual, section 9, and it's all about epf_ntb_peer_spad_bar_set. no cap, it's niche but it's iconic.

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✨ NAME ✨

epf_ntb_peer_spad_bar_set — literally just Set peer scratchpad BAR. that's the whole vibe. 🎀

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🌸 SYNOPSIS 🌸

int epf_ntb_peer_spad_bar_set (struct epf_ntb *ntb , enum
pci_epc_interface_type type );

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🦋 ARGUMENTS 🦋

• ntb — the NTB device that facilitates communication between HOST1 and HOST2. she's the matchmaker fr fr 🫶
• type — PRIMARY interface or SECONDARY interface. pick your fighter 💅

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🔥 DESCRIPTION 🔥

ok so picture this. here's the layout, and yes i'm showing you the diagram because it ate:

┌────────────────────────────────────────────────────────────────┐
│ BAR0                  CONFIG REGION                       BAR0 │
│ BAR1                                  SCRATCHPAD REGION        │
│ BAR2   Local Memory   BAR2                                     │
│ BAR3                  BAR3                                     │
│ BAR4                  BAR4                                     │
│ BAR5                  BAR5                                     │
└────────────────────────────────────────────────────────────────┘
EP CONTROLLER 1                                        EP CONTROLLER 2

so what this function does is set BAR1 of EP CONTROLLER 2, which contains HOST2's peer scratchpad region. ✨

now here's the tea: while BAR1 is the default peer scratchpad BAR, an NTB could have other BARs for peer scratchpad (because of 64-bit BARs or reserved BARs — yeah, it's giving chaos 😭). this function can get the exact BAR used for peer scratchpad from epf_ntb_bar[BAR_PEER_SPAD].

and since HOST2's peer scratchpad is also HOST1's self scratchpad, this function gets the address of peer scratchpad from peer_ntb_epc->epf_ntb_bar[BAR_CONFIG]. iykyk 🧚

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👑 SEE ALSO 👑

kernel file: ./drivers/pci/endpoint/functions/pci-epf-ntb.c

and the whole friend group, no one left out:

• epf_ntb_link_up(9)
• epf_ntb_configure_mw(9)
• epf_ntb_teardown_mw(9)
• epf_ntb_configure_msi(9)
• epf_ntb_configure_msix(9)
• epf_ntb_configure_db(9)
• epf_ntb_teardown_db(9)
• epf_ntb_cmd_handler(9)
• epf_ntb_peer_spad_bar_clear(9)
• epf_ntb_config_sspad_bar_clear(9)
• epf_ntb_config_sspad_bar_set(9)
• epf_ntb_config_spad_bar_free(9)
• epf_ntb_config_spad_bar_alloc(9)
• epf_ntb_config_spad_bar_alloc_interface(9)
• epf_ntb_free_peer_mem(9)
• epf_ntb_db_mw_bar_clear(9)
• epf_ntb_db_mw_bar_cleanup(9)
• epf_ntb_configure_interrupt(9)
• epf_ntb_alloc_peer_mem(9)
• epf_ntb_db_mw_bar_init(9)
• epf_ntb_epc_create_interface(9)
• epf_ntb_epc_create(9)
• epf_ntb_init_epc_bar_interface(9)
• epf_ntb_init_epc_bar(9)
• epf_ntb_epc_init_interface(9)
• epf_ntb_epc_cleanup_interface(9)
• epf_ntb_epc_cleanup(9)
• epf_ntb_epc_init(9)
• epf_ntb_bind(9)
• epf_ntb_unbind(9)
• epf_ntb_add_cfs(9)
• epf_ntb_probe(9)

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this page lives in ./drivers/pci/endpoint/functions, dropped October 2026, and it's part of the Kernel API Manual (section 9, epf_ntb_peer_spad_bar_set(9)). kbye, go read some kernel source 💖🌈⭐