Date: Thu, 10 Jan 2013 16:10:43 -0500 From: John Baldwin <jhb@freebsd.org> To: Alfred Perlstein <alfred@freebsd.org> Cc: svn-src-projects@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r245259 - projects/utrace2 Message-ID: <201301101610.43321.jhb@freebsd.org> In-Reply-To: <201301101758.r0AHw6m7078896@svn.freebsd.org> References: <201301101758.r0AHw6m7078896@svn.freebsd.org>
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On Thursday, January 10, 2013 12:58:06 PM Alfred Perlstein wrote: > Author: alfred > Date: Thu Jan 10 17:58:05 2013 > New Revision: 245259 > URL: http://svnweb.freebsd.org/changeset/base/245259 > > Log: > Project branch for utrace2(2) work. > > The original utrace(2) call from FreeBSD 2.2 did not offer a > standardized way to specify the type of data being traced. Examples, > a utrace(2) record of 3 words is assumed to be a malloc(3) utrace > point, while RTLD uses a string at the start of the utrace record. > > Instead of risking breaking 10+ years of existing code, utrace2 is > introduced which will include "type,version" tuple in the utrace > data to allow utilities such as ktrace to parse them safely. > > Additionally a namespace is provided for both the base system and > for developers wishing to make use of the utrace2(2) system so > there are no collisions. Hummm, when I added the RTLD ones, I figured the convention of using a 4 character signature at the beginning for future traces would suffice just fine (e.g., see ACPI tables and most other BIOS tables that all use 4 char signatures (_32_, $PIR, _MP_, etc.). It seems cumbersome to have a separate ktrace/kdump flag, esp. if the plan is to obsolete utrace(). In that case 'u' should just toggle both. Do you have any new traces you want to add that you couldn't do using the 4 char signature method? -- John Baldwin
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