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Bug #9210

remove KMDB branch debugging support

Added by John Levon almost 2 years ago. Updated over 1 year ago.

Status:
Closed
Priority:
Normal
Assignee:
Category:
-
Start date:
2018-02-28
Due date:
% Done:

100%

Estimated time:
Difficulty:
Medium
Tags:
needs-triage

Description

https://smartos.org/bugview/OS-6565

KMDB has vestigial support for two features, ::step branch and ::branches. The former allows you to step to the next branch point, while the latter reports the "last few" branches, as recorded in MSRs such as the LBR.

However, this was never properly implemented for 64-bit, thus is effectively non-existent on any reasonably modern system. While it could be resurrected, fixing this would complicate KPTI implementation. As it's already broken, it's hard to argue that it will be missed; we'll just remove all the relevant code.

History

#1

Updated by John Levon almost 2 years ago

  • Assignee set to John Levon
#2

Updated by Electric Monk over 1 year ago

  • Status changed from New to Closed
  • % Done changed from 0 to 100

git commit 399ca3a7ff315244c51a7bbd1d3ce2709ef6c7c6

commit  399ca3a7ff315244c51a7bbd1d3ce2709ef6c7c6
Author: John Levon <john.levon@joyent.com>
Date:   2018-04-10T14:36:44.000Z

    9210 remove KMDB branch debugging support
    9211 ::crregs could do with cr2/cr3 support
    9209 ::ttrace should be able to filter by thread
    Reviewed by: Patrick Mooney <patrick.mooney@joyent.com>
    Reviewed by: Yuri Pankov <yuripv@yuripv.net>
    Approved by: Gordon Ross <gwr@nexenta.com>

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