xref: /src/doc/HACKS

# $NetBSD: HACKS,v 1.91.2.1 2007/05/16 20:24:13 jdc Exp $
#
# This file is intended to document workarounds for currently unsolved
# (mostly) compiler bugs.
#
# Format:
#   hack		title
#   cdate		creation date
#   mdate		mod date
#   who			responsible developer
#   port		...
#  	  affected ports, space separated, if not "all"
#   file		affected file : revision : line from : line to
#  	  affected files and revision and line numbers describing hack
#  	  multiple lines if necessary.
#   pr			NNNN ...
#  	  problem reports this hack works around, if known. Space
#  	  separated.
#   regress		src/regress/directory/where/test/found
#  	  regression test directories, if available.
#   descr
#  	  insert short informal description (multi-line). (Longer ones
#  	  should be in the PR database. More formal descriptions might
#  	  be in the regress tree. See above).
#   kcah
#  	  closing bracket.
#
# this is a comment.

hack	netstat ieee1394 address printing.
mdate	14 Nov 2000
who	matt
file	lib/libc/net/getnameinfo.c	: 1.32 : 497 : 503
descr
	Because the current implementation of IP over IEEE1394, the
	fw device address contains more than just the IEEE1394 EUI-64.
	So when printing out IEEE1394 addresses, ignore the extra stuff.
kcah

hack	xterm vs. libterm
mdate	01 Aug 2000
who	jdc
file	xsrc/xc/programs/xterm/main.c	: 1.2 : 3609 : 3614
pr	10383
descr
	In order to extend the termcap string over 1023 bytes, a ZZ entry was
	introduced to point to a memory location containing the full entry.
	Without this hack, xterm will export a termcap containing the ZZ
	entry, which will then be ignored by libterm.  As xterm modifies the
	exported termcap, this would cause those modifications to be ignored.
kcah

hack	wi-at-big-endian-bus
cdate	15 Mar 2002
who	martin
file	dev/ic/wireg.h
descr	Add an option to access the underlying bus in big endian byte order
	to work around deficiencies in bus_space_{read,write}_* macros.
	Those don't allow the implementation of a proper pcmcia bus space
	tag.
kcah

hack	specific knowledge of colours in curses code
cdate	Sun Apr  6 11:05:24 BST 2003
who	jdc
file	lib/libcurses/color.c : r1.24
descr
	Swap red/blue and yellow/cyan colours for COLOR_OTHER.
	Fix is to enhance libtermcap to understand terminfo-style % sequences.
	See also:
	    http://mail-index.NetBSD.org/tech-userlevel/2003/04/06/0000.html
kcah

hack	Compensation for differing types of LINUX_USRSTACK and USRSTACK
cdate	21 Aug 2003
who	he
file	sys/miscfs/procfs/procfs_linux.c : 1.14
descr
	Not all ports have LINUX_USRSTACK and/or USRSTACK defined as
	literals/constants, but refer to variables of a type which is
	not "unsigned long", causing compilation of procfs_linux.c to
	fail with "makes integer from pointer without a cast".  This
	is observed on e.g. the sun3 port.  Ideally the "types" for
	symbols should be consistent across all ports.
kcah

hack	GCC2 isn't C99
cdate	5 December 2003
who	mrg
file	gnu/dist/binutils/ld/ldlex.c: r1.2
descr
	ldlex.c is generated from ldlex.l and we get macro redefinition
	errors from it if __STDC_VERSION__ is not C99 compliant.  This
	hack forces NetBSD 1.6 and later systems to also include <stdint.h>
	to get the relevant definitions.  This hack should be backed out
	when all platforms have switched away from GCC2.
kcah

hack	gcc-strict-aliasing
cdate	6 August 2004
who	junyoung
pr	26516
file	src/usr.sbin/racoon/racoon/Makefile : 1.21
descr
	GCC issues a warning "dereferencing type-punned pointer will break
	strict-aliasing rules" when compiling
	crypto/dist/kame/racoon/crypto/openssl.c with -O[23s]. Note that this
	is due to use of type casting in a non-standard way in the code and
	not a compiler bug. Once a new release of KAME with a proper fix
	applied is imported this should be backed out.
kcah

hack	gcc 3.3.3 wrong uninitialised variable
mdate	12 May 2006
who	he
file	usr.bin/msgc/msg_sys.def : 1.33-1.34
file	distrib/utils/sysinst/aout2elf.c : 1.11
descr
	Gcc 3.3.3 gets some -Wuninitialized warnings wrong.  This is
	just one of many in the tree, marked with
	/* XXX -Wuninitialized [arch] */
	in the source.
kcah

hack	gcc4 wrong uninitialized variable
mdate	10 May 2006
who	mrg
file	bin/ksh/eval.c			: 1.6
file	bin/sh/histedit.c		: 1.39
file	bin/sh/parser.c			: 1.60
file	bin/systrace/systrace.c		: 1.33
file	crypto/dist/heimdal/kdc/524.c	: 1.10
file	crypto/dist/ssh/sftp.c		: 1.20
file	crypto/dist/ssh/ssh-keysign.c	: 1.11
file	dist/ipf/lib/hostname.c		: 1.2
file	dist/ipf/tools/ipmon.c		: 1.8
file	dist/ntp/ntpd/ntp_request.c	: 1.4
file	dist/ntp/ntpd/refclock_shm.c	: 1.4
file	dist/ntp/sntp/timing.c		: 1.3
file	dist/pppd/pppstats/pppstats.c	: 1.3
file	dist/smbfs/lib/smb/rap.c	: 1.6
file	dist/tcpdump/print-zephyr.c	: 1.5
file	distrib/utils/sysinst/aout2elf.c : 1.12
file	gnu/libexec/uucp/uucico/uucico.c : 1.6
file	lib/libc/citrus/citrus_csmapper.c : 1.6
file	lib/libc/citrus/citrus_pivot_factory.c : 1.5
file	lib/libc/inet/inet_cidr_ntop.c	: 1.3
file	lib/libc/inet/inet_ntop.c	: 1.3
file	lib/libc/stdio/vfwprintf.c	: 1.8
file	libexec/ld.elf_so/arch/m68k/mdreloc.c : 1.20
file	libexec/ld.elf_so/arch/powerpc/ppc_reloc.c : 1.40
file	libexec/ld.elf_so/arch/sh3/mdreloc.c : 1.22
file	libexec/ld.elf_so/arch/sparc/mdreloc.c : 1.39
file	libexec/ld.elf_so/arch/sparc64/mdreloc.c : 1.39
file	libexec/ld.elf_so/arch/vax/mdreloc.c	: 1.21
file	libexec/ld.elf_so/arch/x86_64/mdreloc.c	: 1.27
file	sbin/fsck_ext2fs/dir.c		: 1.19
file	sbin/routed/rtquery/rtquery.c	: 1.18
file	sys/arch/amd64/amd64/pmap.c	: 1.26
file	sys/arch/i386/pci/piixpcib.c	: 1.4
file	sys/arch/m68k/m68k/pmap_motorola.c	: 1.4
file	sys/crypto/cast128/cast128.c	: 1.9
file	sys/ddb/db_command.c		: 1.86
file	sys/dev/cardbus/cardbus_map.c	: 1.21
file	sys/dev/fss.c			: 1.25
file	sys/dev/ic/igsfb.c		: 1.39
file	sys/dev/ic/mb86950.c		: 1.5
file	sys/dev/ic/midway.c		: 1.71
file	sys/dev/kttcp.c			: 1.18
file	sys/dev/rasops/rasops_bitops.h	: 1.9
file	sys/dev/pci/cmpci.c		: 1.31
file	sys/dev/pci/machfb.c		: 1.45
file	sys/dev/usb/ohci.c		: 1.174
file	sys/dev/usb/uhci.c		: 1.196
file	sys/dev/rasops/rasops_bitops.h	: 1.9
file	sys/dist/ipf/netinet/ip_nat.c	: 1.10
file	sys/dist/ipf/netinet/ip_rpcb_pxy.c : 1.8
file	sys/dist/pf/net/pf.c		: 1.22
file	sys/fs/udf/udf_vnops.c		: 1.4
file	sys/kern/kern_sig.c		: 1.219
file	sys/kern/tty.c			: 1.181
file	sys/net/bpf.c			: 1.116
file	sys/net/zlib.c			: 1.26
file	sys/netccitt/if_x25subr.c	: 1.37
file	sys/netinet/in.c		: 1.107
file	sys/netsmb/smb_smb.c		: 1.27
file	sys/netsmb/smb_trantcp.c	: 1.22
file	sys/nfs/nfs_serv.c		: 1.108
file	sys/nfs/nfs_socket.c		: 1.129
file	sys/nfs/nfs_syscalls.c		: 1.91
file	sys/ufs/lfs/lfs_vfsops.c	: 1.207 [also (char *)]
file	usr.bin/ftp/ftp.c		: 1.140
file	usr.bin/find/function.c		: 1.54
file	usr.bin/mail/tty.c		: 1.20
file	usr.bin/nl/nl.c			: 1.7
file	usr.bin/systat/keyboard.c	: 1.23
file	usr.bin/usbhidctl/usbhid.c	: 1.29
file	usr.bin/vi/cl/cl_read.c		: 1.5
file	usr.bin/vi/ex/ex_cscope.c	: 1.12
file	usr.bin/vi/ex/ex_tag.c		: 1.19
file	usr.bin/vi/vi/v_txt.c		: 1.15
file	usr.sbin/altq/altqstat/qdisc_rio.c : 1.4
file	usr.sbin/cron/do_command.c	: 1.19
file	usr.sbin/timed/timed/slave.c	: 1.15
descr
	GCC 4.1 gets many uninitialised variable warnings wrong.  We should
	really audit all the old hacks like this when older compilers are
	removed from the tree, as many are probably no longer required.
	The problem is that it does not recognize initialization via function
	call pointer. I.e.
		int p;
		foo(&p);
	does not mark p as initialized.
kcah

hack	gcc4 pointer sign and strict aliasing problems
mdate	10 May 2006
who	mrg
file	bin/ed/Makefile			: 1.33
file	bin/systrace/Makefile		: 1.12
file	distrib/utils/sysinst/Makefile.inc : 1.44
file	distrib/utils/x_dhclient/Makefile : 1.15
file	games/bcd/Makefile		: 1.5
file	games/dab/Makefile		: 1.5
file	games/larn/Makefile		: 1.17
file	games/pom/Makefile		: 1.5
file	lib/libasn1/Makefile		: 1.26
file	lib/libcrypt/Makefile		: 1.17
file	lib/libgssapi/Makefile		: 1.16
file	lib/libhdb/Makefile		: 1.20
file	lib/libkadm5clnt/Makefile	: 1.21
file	lib/libkadm5srv/Makefile	: 1.25
file	lib/libkrb5/Makefile		: 1.35
file	lib/libssh/Makefile		: 1.6
file	lib/libtelnet/Makefile		: 1.26
file	libexec/getty/Makefile		: 1.14
file	libexec/kadmind/Makefile	: 1.19
file	libexec/kpasswdd/Makefile	: 1.14
file	sbin/atactl/Makefile		: 1.3
file	sbin/cgdconfig/Makefile		: 1.7
file	sbin/clri/Makefile		: 1.13
file	sbin/dkctl/Makefile		: 1.4
file	sbin/dump/Makefile		: 1.33
file	sbin/fdisk/Makefile		: 1.35
file	sbin/fsck_ext2fs/Makefile	: 1.11
file	sbin/fsck_ffs/Makefile		: 1.29
file	sbin/fsdb/Makefile		: 1.18
file	sbin/mount_smbfs/Makefile	: 1.4
file	sbin/newfs/Makefile		: 1.30
file	sbin/newfs_sysvbfs/Makefile	: 1.2
file	sbin/restore/Makefile		: 1.23
file	sbin/veriexecctl/Makefile	: 1.11
file	sys/lib/libsa/Makefile		: 1.59
file	sys/arch/evbarm/adi_brh/brh_machdep.c : 1.24
file	usr.bin/awk/Makefile		: 1.9
file	usr.bin/crontab/Makefile	: 1.24
file	usr.bin/ctags/Makefile		: 1.8
file	usr.bin/gzip/Makefile		: 1.10
file	usr.bin/ssh/sftp/Makefile	: 1.10
file	usr.bin/ssh/ssh/Makefile	: 1.25
file	usr.bin/vi/build/Makefile	: 1.26
file	usr.bin/telnet/Makefile		: 1.40
file	usr.bin/tn3270/tn3270/Makefile	: 1.36
file	usr.bin/tr/Makefile		: 1.4
file	usr.sbin/amd/amd/Makefile	: 1.27
file	usr.sbin/amd/amq/Makefile	: 1.14
file	usr.sbin/amd/libamu/Makefile	: 1.20
file	usr.sbin/amd/pawd/Makefile	: 1.5
file	usr.sbin/bind/Makefile.inc	: 1.22
file	usr.sbin/bind/libdns/Makefile	: 1.3
file	usr.sbin/bind/named/Makefile	: 1.17
file	usr.sbin/bootp/bootptest/Makefile : 1.2
file	usr.sbin/chrtbl/Makefile	: 1.6
file	usr.sbin/cron/Makefile		: 1.12
file	usr.sbin/dhcp/Makefile.inc	: 1.20
file	usr.sbin/dumplfs/Makefile	: 1.11
file	usr.sbin/hprop/Makefile		: 1.13
file	usr.sbin/installboot/Makefile	: 1.35
file	usr.sbin/ipf/ipftest/Makefile	: 1.32
file	usr.sbin/isdn/isdnd/Makefile	: 1.6
file	usr.sbin/isdn/isdnmonitor/Makefile : 1.3
file	usr.sbin/isdn/isdntel/Makefile	: 1.2
file	usr.sbin/isdn/isdntrace/Makefile : 126
file	usr.sbin/mopd/common/Makefile	: 1.10
file	usr.sbin/mopd/mopd/Makefile	: 1.9
file	usr.sbin/mopd/mopprobe/Makefile	: 1.7
file	usr.sbin/makefs/Makefile	: 1.17
file	usr.sbin/mscdlabel/Makefile	: 1.5
file	usr.sbin/pkg_install/add/Makefile : 1.7
file	usr.sbin/pkg_install/create/Makefile : 1.5
file	usr.sbin/pkg_install/lib/Makefile : 1.28
file	usr.sbin/ntp/ntpd/Makefile	: 1.10/1.11
file	usr.sbin/ntp/ntptime/Makefile	: 1.4/1.5
file	usr.sbin/pppd/Makefile.inc	: 1.3
file	usr.sbin/pppd/pppd/Makefile	: 1.38
file	usr.sbin/rarpd/Makefile		: 1.10
file	usr.sbin/rbootd/Makefile	: 1.10
file	usr.sbin/rpc.pcnfsd/Makefile	: 1.17
file	usr.sbin/rtadvd/Makefile	: 1.9
file	usr.sbin/tcpdump/Makefile	: 1.42
file	usr.sbin/wiconfig/Makefile	: 1.3
descr
	GCC 4.1 warns on pointer sign comparision/assignments and lots of
	code does not conform.  For now we use -Wno-pointer-sign and
	-fno-strict-aliasing.
kcah

hack	rbus resource allocation work around
cdate	10 May 2007
who	jnemeth
file	src/sys/dev/pcmcia/aic_pcmcia.c : 1.35
pr	26909 31245
descr
	On some cards, the card align field property value interferes
	with the rbus resource allocation causing the card not to
	configure properly.  Setting it to 0 fixes the problem but it
	is not the proper solution.
kcah

port	vax

	hack	gcc4/vax compiler crash
	cdate	Fri Jun 30 22:39:12 PDT 2006
	who	mrg
	file	bin/csh/Makefile	: 1.27
	file	lib/i18n_module/UTF7/Makefile	: 1.2
	descr
		GCC4 on vax crashes.  -O0 stops it happening so far...
	kcah

	hack	gcc 2.95/vax doesn't like abort being used as function pointer
	cdate	Tue Dec 13 05:54:50 GMT 2005
	who	jmc
	file	lib/libc/rpc/svc_vc.c 1.15
	descr
		Provide a local definition for abort which doesn't include
		the noreturn attribute which trips up gcc 2.95 on vax.
	kcah
	
	hack	gcc 2.95/vax doesn't have stdbool.h and gettext needs it
	cdate	Mon May  9 12:16:22 CDT 2005
	who	jmc
	file	gnu/usr.bin/gettext/Makefile.inc.prog 1.5
		gnu/usr.bin/gettext/libgrep/Makefile 1.3
		gnu/usr.bin/gettext/libnlspr/Makefile 1.5
		gnu/usr.bin/gettext/libnlsut/Makefile 1.3   
	descr
		The latest gettext assumes a C99 environment or at least
		configure checks to work around this. As we don't use configure
		provide a stdbool.h for vax builds locally in directories from
		the template provided by the gettext code.
	kcah
	
	hack	gcc 2.95/vax cannot handle __builtin_ffs()
	cdate	Fri Aug 23 21:31:15 CEST 2002
	who	ragge
	file	sys/lib/libkern/libkern.h : 1.42
	descr
		__builtin_ffs() is ifdef'd away if __vax__. Matt Thomas has
		added this feature to GCC 3 so it can be removed when switching.
	kcah

	hack	gcc-vax-libbz2
	mdate	27 Jun 2002
	who	thorpej
	file	lib/libbz2/Makefile
	descr
		libbz2 is mis-compiled with optimization with GCC 2.95.3
		on VAX.  -O0 works around this problem.
	kcah

	hack	vax Toolchain bug
	cdate	28 Mar 2003
	who	he
	file	sys/arch/vax/vax/intvec.S : 1.5
	descr
		Workaround for PR toolchain/20924.  The assembler apparently
		tries to range-check byte offsets when it doesn't have
		sufficient information to make that decision.
		Workaround uses `brw' instead of `brb' instruction.
	kcah

	hack	vax gcc 2.95.3 -Wuninitialized workarounds
	cdate	6 Nov 2003
	who	he
	file	sys/dev/bi/if_ni.c : 1.22
	file	sys/arch/vax/vax/ctu.c : 1.20
	descr
		Workaround for gcc 2.95.3 failing to detect that certain
		variables will be initialized; so that this code compiles
		with -Wuninitialized.  Should be reviewed and possibly
		reverted when gcc 3.3.2 is ready for vax.
	kcah

	hack	vax gcc 2.95.3 structure initialization
	cdat	13 May 2004
	who	cl
	file	sys/miscfs/kernfs/kernfs_vnops.c : 1.104
	descr
		Workaround for gcc 2.95.3 failing to initialize structures
		and/or unions inside structures using nested designators.
		Should be reverted when gcc >=3.3.3 is ready for vax.
	kcah

	hack	vax gcc 2.95.3 needs -I. to build nslexer.c
	cdat	6 Jun 2004
	who	mhitch
	file	lib/libc/arch/vax/Makefile.inc : 1.6
	descr
		It appears necessary to add -I. to CPPFLAGS when building
		nslesxer.c.  This may be caused by gcc 2.95.3 being used.
		Should be reverted when a newer gcc is ready for vax.
	kcah

	hack	vax gcc 2.95.3 doesn't understand "-std=c99"
	cdat	5 April 2005
	who	tron
	file	src/share/mk/bsd.sys.mk
	descr
		We cannot use "-std=c99" for compiler warning level 4 and above
		because gcc 2.95.3 doesn't support that option.
	kcah

	hack	declare boolean_t in two IPF user-mode programs
	cdate	Tue Mar  7 19:19:20 CET 2006
	who	he
	file	dist/ipf/ipsend/iptests.c : 1.8
		dist/ipf/ipsend/sock.c : 1.7
	descr
		The IPF user-mode programs ipsend and iptest first
		include <sys/types.h> without _KERNEL defined, and
		later include <sys/file.h> with _KERNEL defined.
		This causes a build failure when building for vax,
		since <sys/device.h> ends up being included without
		bollean_t being defined by <sys/types.h>.
		Build failure and further details documented in
		PR#32907.
	kcah

port	arm

	hack	gcc-unsigned-compare
	cdate	09 Mar 2002
	mdate	18 Mar 2002
	who	bjh21
	file	dist/bind/lib/nameser/ns_parse.c : 1.3
	file	dist/dhcp/minires/ns_parse.c : 1.3
	file	dist/dhcp/omapip/result.c : 1.2
	file	dist/dhcp/server/failover.c : 1.3
	file	gnu/dist/toolchain/bfd/bfd.c : 1.2
	file	gnu/dist/toolchain/bfd/format.c : 1.2
	file	gnu/dist/toolchain/gdb/target.c : 1.2
	file	sys/kern/vfs_subr.c : 1.172
	descr	When checking that a potentially-unsigned enum is >= 0, assign
		it to an int first.  This is necessary to avoid "comparison is
		always true" warnings with -fshort-enums.  Casting to an int
		really should be enough, but turns out not to be.
	kcah

	hack	gcc 3.3.2/arm sys/kern/uipc_socket.c
	cdate	Tue Oct 28 18:02:16 GMT 2003
	who	skrll
	pr	23044
	file	sys/arch/arm/conf/Makefile.arm : 1.19
	descr
		Performing a build.sh tools on a CATS with NFS mounted 
		obj and src directories results in "panic: receive 1"
		The hack is to compile sys/kern/uipc_socket.c with
		-fno-strict-aliasing
	kcah


port	pc532

	hack	egcs-pc532-ip6_mroute
	cdate	09 Jul 2002
	who	simonb
	file	sys/arch/pc532/conf/Makefile.pc532 : 1.70
	file	sys/arch/pc532/conf/files.pc532 : 1.47
	descr
		egcs 1.1.2 gets an "internal error--insn does not satisfy its
		constraints" error compiling ip6_mroute.c with -O2 or greater.
		-O1 works around this problem.
	kcah

	hack	gcc-pc532-duffs_device
	cdate	Mon Oct 27 07:23:05 UTC 2003
	who	simonb
	file	sys/arch/pc532/conf/Makefile.pc532 : 1.71
	file	sys/arch/pc532/conf/files.pc532 : 1.52
	pr	GCC PR optimization/5230
	descr
		gcc incorrectly gives an "unreachable code at beginning of
		switch statement" for a Duff's device construct in
		arch/pc532/dev/ncr.c.  There is no way to disable just this
		warning, so -Wno-error is turned on for this file.
	kcah

	hack	gcc332-cppmacro-ice
	cdate	Sun Dec  7 12:48:33 UTC 2003
	who	simonb
	file	gnu/usr.bin/gcc3/libcpp/Makefile : 1.2
	descr
		gcc 3.3.2 gets an ICE when compiling cppmacro.c with -O2.
		The hack is to use -O1 for this file.  Fixed in gcc
		-current mainline, unable to work out where the fix is
		right now.
	kcah


port	sh3

	hack	gcc4-sh3-bz2
	mdate	20 May 2006
	who	mrg
	file	lib/libbz2/Makefile	: 1.10
	descr
		The in-tree GCC 4.1-based compiler generated too-far
		pc-relative addresses.  Hack is to build with -O0.
	kcah


port	sh5

	hack	SuperH SH5 Toolchain Bugs
	cdate	11 Jul 2002
	who	scw
	file	usr.sbin/ndbootd/ndbootd.c : 1.6
	file	usr.sbin/traceroute/traceroute.c : 1.48
	descr
		The SuperH SH5 toolchain (2.97-sh5-010522) gets an internal
		compiler error when assigning a bit-wise inverted value
		under some circumstances.
		Work around it by splitting the statement into two.
	kcah

	hack	SuperH SH5 Toolchain Bugs
	cdate	17 May 2003
	who	scw
	file	lib/libpthread/pthread_lock.c : 1.7
	descr
		The SuperH SH5 toolchain generates incorrect PIC code when
		faced with a symbol which is declared extern, but has local
		scope due to being defined within an asm() statement (without
		being declared .globl in that statement). Work around it by
		adding the .globl.
	kcah

	hack	gcc 3.3.2 on sh5 - ICE compiling reload1.c at -O2
	cdate	Sun Dec  7 19:44:05 GMT 2003
	who	scw
	file	gnu/usr.bin/gcc3/backend/Makefile : 1.13
	descr
		Gcc3 for sh5 gets an ICE compiling reload1.c at -O2.
		Drop to -O1 for now when building for sh5.
	kcah

	hack	gcc 3.3.2 on sh5 - ICE compiling elf32.c/elf64.c at -O2
	cdate	Sun Dec  7 21:10:46 GMT 2003
	who	scw
	file	gnu/lib/libbfd/Makefile : 1.39
	descr
		Gcc3 for sh5 gets an ICE compiling libbfd's elf32.c
		and elf64.c at -O2.
		Drop to -O1 for now when building for sh5.
	kcah


	hack	gcc 3.3.2 on sh5 - fatal warning compiling function.c
	cdate	Sun Dec  7 19:44:05 GMT 2003
	who	scw
	file	gnu/usr.bin/gcc3/backend/Makefile : 1.13
	descr
		Gcc3 for sh5 issues a warning:
		.../gnu/dist/gcc/gcc/function.c:4742: warning: `and' of
		    mutually exclusive equal-tests is always 0.
		This causes the build to fail because of -Werror.
		Work-around by defining NOGCCERROR when building for sh5.
	kcah

	hack	gcc 3.3.3 on sh5 - ICE compiling rbtdb.c and rbtdb64.c
	cdate	Thu Nov 11 00:35:33 UTC 2004
	who	he
	file	usr.sbin/bind/libdns/Makefile/1.2
	descr
		Gcc3 for sh5 gets an ICE compiling these files at -O2.
		Drop to -O1 for now when building for sh5.
	kcah

	hack	gcc 3.3.3 nb3 on sh5 - ICE compiling bsd-comp.c
	cdate	Thu May 25 23:05:20 UTC 2005
	who	he
	file	sys/lkm/net/bsdcomp/Makefile : 1.3
	descr
		Gcc3 for sh5 gets an ICE compiling this at -O2,
		"could not split insn".  Drop to -O1 for sh5.
	kcah

	hack	gcc 3.3.3 nb3 on sh5 - ICE compiling strtod.c
	cdate	Tue Jan 31 10:51:52 GMT 2006
	who	scw
	file	lib/libc/gdtoa/Makefile.inc : 1.2
	descr
		Gcc3 for sh5 gets an ICE compiling this at -O2,
		"could not split insn".  Drop to -O1 for sh5.
	kcah

port	sun2

	hack	gcc 3.3.2/mdsetimage
	cdate	Tue Oct 28 18:43:05 EST 2003
	who	fredette
	file	gnu/usr.sbin/mdsetimage/Makefile : 1.15
	descr
		mdsetimage.c causes cc1 to barf for as-yet unknown reasons.
		this hack uses -O0 to avoid the problem.
	kcah

	hack	gcc 3.3.2/installboot/ffs.c
	cdate	Tue Oct 28 18:43:05 EST 2003
	who	fredette
	file	usr.sbin/installboot/Makefile : 1.26
	descr
		ffs.c causes cc1 to barf for as-yet unknown reasons.  this
		hack uses -O0 to avoid the problem.
	kcah

	hack	gcc 4.1.1/fsck_ffs/pass1.c
	cdate	Fri Jun 23 10:30:25 PDT 2006
	who	mrg
	file	sbin/fsck_ffs/Makefile : 1.30
	file	sbin/fsdb/Makefile : 1.19
	file	sbin/dump_lfs/Makefile : 1.9
	file	usr.sbin/ndbootd/Makefile : 1.2
	descr
		pass1.c causes cc1 to barf for as-yet unknown reasons.  this
		hack uses -O0 to avoid the problem. (these all seem to be the
		same problem.)
	kcah


port	m68000

	hack	gcc 3.3.2/gcc/ra-colorize.c
	cdate	Wed Nov  5 11:03:13 EST 2003
	who	mrg
	file	gnu/usr.bin/gcc3/backend/Makefile : 1.11
	descr
		ra-colorize.c causes a whole spew of unreferenced .L* local
		symbols.  using -O0 (or even -O2 reportedly) avoids the problem.
		Note this has been fixed in 3.3.3 at least on m68k,
		but it hasn't been confirmed on sun2/m68000.
		(it's too slow even on emulator and unlikely to build
		 toolchains on sun2 with its maximum 4MB RAM)
	kcah

port	sparc64

	hack	disable optimzations for uvm_bio.c on 32 bit kernels
	cdate	Sun Mar 21 14:14:04 MET 2004
	who	martin
	file	sys/arch/sparc64/conf/Makefile.sparc64 : 1.53-1.54
	file	sys/arch/sparc64/conf/files.sparc64 : 1.93
	descr
		The sparc compiler miscompiles uvm_bio.c when using
		any optimization. This results in ubc_release panics.
	kcah

port	macppc

	hack	remove inline from rotate_{left,right}
	cdate	Tue Feb 22 13:43:25 EST 2005
	who	christos
	file	src/dist/bind/lib/dns/rbt.c
	descr
		The macppc gcc-3.3 compiler miscompiles rbt.c when these
		functions are inlined. The error is:
		.* named[368]: rbt.c:1584: INSIST(child != (void *)0) >failed
		.* named[368]: exiting (due to assertion failure)
		This is reportedly fixed in gcc-3.4
	kcah

port	mips

	hack	mips-shared-linker-load-address
	cdate	Fri Oct  7 08:33:10 UTC 2005
	who	simonb
	file	src/sys/kern/exec_elf32.c : 1.107
	descr
		With COMPAT_16 or previous enabled (which enables
		ELF_INTERP_NON_RELOCATABLE) a recent ld.elf_so will
		load and run at address 0.  The check to fix this in
		rev 1.107 only checks the first psection of the ELF
		executable, which may not be loadable.  A more correct
		fix is to check the first loadable psection instead of
		just the first psection.
	kcah

	hack	mips-duplicate-ras-end-label
	cdate	Sat Sep  2 23:29:42 2006
	who	martin
	file	src/regres/sys/kern/ras/ras3/Makefile : 1.3
	descr
		Add -fno-reorder-blocks to CFLAGS to avoid duplicate
		labels by duplicated __asm output from RAS_END()
		macro.
	kcah

port	i386

	hack	minus-Os-broken-machdep-c
	cdate	Mon Jul 31 13:09:01 EDT 2006
	who	christos
	file	src/sys/arch/machdep.c : 1.576
	descr
		gcc-4 miscompiles this file with -Os and the resulting
		kernel resets as reported in PR33725
	kcah

	hack	use volatile intermediate variable to enforce rounding
	cdate	Tue Aug  1 22:15:55 MEST 2006
	who	drochner
	file	src/lib/libm/src/lrintf.c : 1.4
	file	src/lib/libm/src/s_rintf.c : 1.8
	descr
		gcc-4 does subsequent operations on "float" values within
		the i387 FPU without rounding the intermediate results
	kcah