Re: kern/58225 - netbsd9/amd64 requires COMPAT_16 for 32bit support

[gnats-admin%netbsd.org@localhost]

The following reply was made to PR kern/58225; it has been noted by GNATS.

From: Paul Goyette <paul%whooppee.com@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/58225 - netbsd9/amd64 requires COMPAT_16 for 32bit support
Date: Tue, 20 Aug 2024 18:10:54 -0700 (PDT)

 OK, I think I've got this understood now...
 
 The changes that were made in compat_netbsd32_signal.c rev 1.53 and 1.54
 are just plain wrong.  These changes cause every netbsd32 image to load
 all of the compat code all the way back to _16.  This is a "backwards
 dependency" where -current depends on older code;  a correct ordering
 would be having the older code depend on the newer (as can be seen in
 all the MODULE(compat_netbsd32_*) modules' required-lists.
 
 IMHO the right thing to do would be to move the relevant code out of
 src/sys/compat/netbsd32/netbsd32_compat_16.c and into
 src/sys/compat/netbsd32/netbsd32_signal.c  That would leave only
 the machdep code for sigreturn14.  (The module init/fini changes in
 rev 1.5 should remain, too.)
 
 As a result, signal code will have everything it needs without using
 a reverse-dependency.  It also simplifies things by removing the need
 to keep track of the *_valid stuff.  (It also removes the need to
 prevent any unload of the compat_netbsd32_16 module - the stuff using
 ``p->p_lflag & PL_SIGCOMPAT''.)
 
 A reproducer for the problem should be simple.  First you modload
 the compat_netbsd32 module.  Then run an image that uses the module
 (preferably a 32-bit netbsd-9 or earlier).  Observe with modstat(8)
 that all compat_xx and compat_netbsd32_xx modules have been loaded.
 
 
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