Messages in this thread | | | From | Itai Nahshon <> | Subject | Questions: SCSI host adapter detection and registration | Date | Tue, 26 Mar 2002 03:51:27 +0200 |
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I have some questions about SCSI host adapter detection and registration.
I'm looking a the code in scsi/scsi.c, scsi/hosts.c and sample scsi host adapter drivers.
For simplicity, I assume the host adapter driver is in a module and it's just loaded (insights about hot-pluggable devices are welcome).
Here are the major steps as I understand them: 1. Module init code calling scsi_register_module() which immediately calls scsi_register_hosts(). 2. scsi_register_host() calls the driver's detect function. 3. The driver's detect function calls scsi_register() for each host (or is it bus?) that it detects. 4. The driver's detect function returns 0 if nothing detected. non zero if a host adapter was detected.
My questions: a. Is any lock held when scsi_register_hosts() is called? b. scsi_register_hosts() protects the detect call with io_request_lock _only_ if use_new_eh_code. Why? c. If a host was detected, there is a code that checks if next_scsi_host was actually incremented... Are there drivers that do not call scsi_register() ? Is it for historical or real reason? Is it possible (at least in theory) that some driver will change next_scsi_host behind our back (hot-pluggable devices)?
Thank you very much, -- Itai
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