Please document how the *-log command outputs are ordered

[martinvonwittich]

When I run a command like nvme error-log /dev/ng1n1 on my computer, I get a list of error log entries, in my case from entry 0 to entry 15:

Details

host ~ # nvme error-log /dev/ng1n1
Error Log Entries for device:ng1n1 entries:16
.................
 Entry[ 0]   
.................
error_count	: 17
sqid		: 0
cmdid		: 0x6010
status_field	: 0x2002(Invalid Field in Command: A reserved coded value or an unsupported value in a defined field)
phase_tag	: 0x1
parm_err_loc	: 0x28
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[ 1]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[ 2]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[ 3]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[ 4]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[ 5]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[ 6]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[ 7]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[ 8]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[ 9]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[10]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[11]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[12]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[13]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[14]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................
 Entry[15]   
.................
error_count	: 0
sqid		: 0
cmdid		: 0
status_field	: 0(Successful Completion: The command completed without error)
phase_tag	: 0
parm_err_loc	: 0
lba		: 0
nsid		: 0
vs		: 0
trtype		: The transport type is not indicated or the error is not transport related.
cs		: 0
trtype_spec_info: 0
.................

Unfortunately, the log entries don't seem to contain timestamps, and I can't find any documentation about the order, so I was confused if the most recent entry is entry 0, or entry 15. https://github.com/linux-nvme/nvme-cli/blob/master/Documentation/nvme-error-log.txt didn't give me any hint.

In the end I had to look it up in the NVMe specification: https://nvmexpress.org/wp-content/uploads/NVM-Express-Base-Specification-Revision-2.3-2025.08.01-Ratified.pdf

5.2.12.1.2 Error Information (Log Page Identifier 01h)
This error log may return the last n errors. If the host specifies a data transfer of the size of n error logs,
then the error logs for the most recent n errors are returned. The ordering of the entries is based on the
time when the error occurred, with the most recent error being returned as the first log entry.

I think it would be helpful if this would be documented :)

[igaw]

As you found out, it is documented in the spec. I really want to avoid duplicating the spec in our documentation, this will not get ouf sync too fast and the result is worse. We could add note that all fields are described in the spec. Care to send a PR/patch?

[ikegami-t]

Just created the PR: #3344 for this issue.