Re: kern/53590: DTrace fbt_getargdesc() fails with "Unknown function"

[christos%zoulas.com@localhost (Christos Zoulas)]

The following reply was made to PR kern/53590; it has been noted by GNATS.

From: christos%zoulas.com@localhost (Christos Zoulas)
To: Andreas Gustafsson <gson%gson.org@localhost>
Cc: gnats-bugs%NetBSD.org@localhost
Subject: Re: kern/53590: DTrace fbt_getargdesc() fails with "Unknown function"
Date: Tue, 11 Sep 2018 17:09:09 -0400

 On Sep 11, 10:55pm, gson%gson.org@localhost (Andreas Gustafsson) wrote:
 -- Subject: Re: kern/53590: DTrace fbt_getargdesc() fails with "Unknown funct
 
 | Christos Zoulas wrote:
 | > You need a fully modular kernel for dtrace to work, otherwise the ctf
 | > tables overflow and you only get the bupkis symbol.
 | 
 | Looks like you are talking about the CTF typeid overflow issue discussed in
 | https://mail-index.netbsd.org/tech-kern/2017/10/13/msg022436.html , but I
 | believe that is a different problem.  My GENERIC kernels don't even have
 | enough type entries to overflow the table:
 | 
 | netbsd-8.0# ctfdump /netbsd | grep "total number of types"
 |   total number of types               = 617
 | 
 | netbsd-current# ctfdump /netbsd | grep "total number of types"
 |   total number of types               = 816
 | 
 | More to the point, this PR is about a lack of function entries, not
 | type entries.  The GENERIC kernel in the 8.0 release and in the latest
 | daily build both have only a single dummy function in the "Functions"
 | section of the ctfdump output:
 | 
 | - Functions ------------------------------------------------------------------
 | 
 |   [19881] FUNC (_debugsym_dummyfunc) returns: 608 args: (683)
 | 
 | - Types ----------------------------------------------------------------------
 | 
 | Same thing when I build a release myself using "build.sh release".
 | However, if I manually build a kernel using "build.sh kernel.gdb=GENERIC",
 | that not only builds a (huge) netbsd.gdb, but also overwrites the netbsd
 | (without the .gdb suffix) from "build.sh release" with an only slightly
 | larger one (27 megabytes instead of 26), and that one *does* include
 | CTF function entries, 34956 of them, including one for vmem_alloc:
 
 So something else broke recently... I will need to take a look.
 
 Thanks,
 
 christos