host_trace_buffer_show(9)

✨ host_trace_buffer_show(9) ✨ — Kernel API Manual

🎀 NAME 🎀

host_trace_buffer_show — firmware ring buffer (trace only) 💫

🦋 SYNOPSIS 🦋

ssize_t host_trace_buffer_show (struct device *cdev , struct device_attribute *attr , char *buf );

🌸 ARGUMENTS 🌸

• cdev — pointer to embedded class device 🫶
• attr — ? (the original page literally says ?, bestie 😭)
• buf — the buffer returned 💖

💅 DESCRIPTION 💅

Okay so this is a sysfs 'read/write' shost attribute. Periodt.

Here’s the important bit, bestie: you will only be able to read 4k bytes of ring buffer at a time. In order to read beyond 4k bytes, you will have to write out the offset to the same attribute, and it will move the pointer. No cap, that’s the whole little dance. ✨

👑 SEE ALSO 👑

Kernel file ./drivers/scsi/mpt3sas/mpt3sas_ctl.c — plus the whole squad: enum block_state(9), _ctl_display_some_debug(9), mpt3sas_ctl_done(9), _ctl_check_event_type(9), mpt3sas_ctl_add_to_event_log(9), mpt3sas_ctl_event_callback(9), _ctl_verify_adapter(9), mpt3sas_ctl_pre_reset_handler(9), mpt3sas_ctl_clear_outstanding_ioctls(9), mpt3sas_ctl_reset_done_handler(9), _ctl_fasync(9), _ctl_poll(9), _ctl_set_task_mid(9), _ctl_send_mctp_passthru_req(9), _ctl_do_mpt_command(9), _ctl_getiocinfo(9), _ctl_eventquery(9), _ctl_eventenable(9), _ctl_eventreport(9), _ctl_do_reset(9), _ctl_btdh_search_sas_device(9), _ctl_btdh_search_pcie_device(9), _ctl_btdh_search_raid_device(9), _ctl_btdh_mapping(9), _ctl_diag_capability(9), _ctl_diag_get_bufftype(9), _ctl_diag_register_2(9), mpt3sas_enable_diag_buffer(9), _ctl_diag_register(9), _ctl_diag_unregister(9), _ctl_diag_query(9), mpt3sas_send_diag_release(9), _ctl_diag_release(9), _ctl_diag_read_buffer(9), _ctl_addnl_diag_query(9), _ctl_enable_diag_sbr_reload(9), _ctl_compat_mpt_command(9), _ctl_ioctl_main(9), _ctl_get_mpt_mctp_passthru_adapter(9), mpt3sas_get_device_count(9), _ctl_ioctl(9), _ctl_mpt2_ioctl(9), _ctl_ioctl_compat(9), _ctl_mpt2_ioctl_compat(9), version_fw_show(9), version_bios_show(9), version_mpi_show(9), version_product_show(9), version_nvdata_persistent_show(9), version_nvdata_default_show(9), board_name_show(9), board_assembly_show(9), board_tracer_show(9), io_delay_show(9), device_delay_show(9), fw_queue_depth_show(9), host_sas_address_show(9), logging_level_show(9), fwfault_debug_show(9), ioc_reset_count_show(9), reply_queue_count_show(9), BRM_status_show(9), host_trace_buffer_size_show(9), host_trace_buffer_enable_show(9), diag_trigger_master_show(9), diag_trigger_master_store(9), diag_trigger_event_show(9), diag_trigger_event_store(9), diag_trigger_scsi_show(9), diag_trigger_scsi_store(9), diag_trigger_mpi_show(9), diag_trigger_mpi_store(9), drv_support_bitmap_show(9), enable_sdev_max_qd_show(9), enable_sdev_max_qd_store(9), sas_address_show(9), sas_device_handle_show(9), sas_ncq_prio_supported_show(9), sas_ncq_prio_enable_show(9), mpt3sas_ctl_init(9), mpt3sas_ctl_release(9), mpt3sas_ctl_exit(9).

💌 source/version: ./drivers/scsi/mpt3sas · date: October 2026 · page: host_trace_buffer_show(9) — catch u later, bestie! 💖