PR/54994 CVS commit: src/sys/arch/powerpc/include

["Rin Okuyama" <rin%netbsd.org@localhost>]

The following reply was made to PR kern/54994; it has been noted by GNATS.

From: "Rin Okuyama" <rin%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/54994 CVS commit: src/sys/arch/powerpc/include
Date: Fri, 21 Feb 2020 12:56:37 +0000

 Module Name:	src
 Committed By:	rin
 Date:		Fri Feb 21 12:56:37 UTC 2020
 
 Modified Files:
 	src/sys/arch/powerpc/include: param.h
 
 Log Message:
 Reduce UPAGES from 2 to 1 for ibm4xx, which was originally 1 and bumped
 to 2 in rev 1.29:
 
     http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/arch/powerpc/include/param.h#rev1.29
 
 Since page size is 16KB on ibm4xx, USPACE is still 16KB, which is the
 same size as on other powerpc processors.
 
 This avoids kernel crash described in PR kern/54994. Also, even if the
 PR is resolved, fork(2) easily fails with ENOMEM if UPAGES is 2, which
 requires physically contiguous pages for u-area. No bad side effect is
 observed as far as I can see.
 
 XXX
 Even with this commit, kern/54994 still critically affects other archs
 with __HAVE_CPU_UAREA_ROUTINES, i.e., alpha, mips, powerpc/{oea,booke},
 and riscv.
 
 
 To generate a diff of this commit:
 cvs rdiff -u -r1.31 -r1.32 src/sys/arch/powerpc/include/param.h
 
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.