boot2 overflow when building with clang

[John Baldwin]

On Wednesday, March 07, 2012 7:18:56 pm Jung-uk Kim wrote:
> On Tuesday 06 March 2012 11:51 pm, Jia-Shiun Li wrote:
> > I am not familiar with boot2, but it looks like allocated size for
> > boot2 is not enough to hold code generated by clang. Reverting
> > r232570 fixes it.
> >
> > ===> sys/boot/i386/boot2 (all)
> > objcopy -S -O binary boot1.out boot1
> > dd if=/dev/zero of=boot2.ldr bs=512 count=1
> > clang -Os  -fno-guess-branch-probability  -fomit-frame-pointer
> > -fno-unit-at-a-time  -mno-align-long-strings  -mrtd  -mregparm=3
> > -DUSE_XREAD  -DUFS1_AND_UFS2  -DFLAGS=0x80  -DSIOPRT=0x3f8
> > -DSIOFMT=0x3  -DSIOSPD=9600
> > -I/usr/src/sys/boot/i386/boot2/../../common
> > -I/usr/src/sys/boot/i386/boot2/../btx/lib -I.  -Wall
> > -Waggregate-return -Wbad-function-cast -Wcast-align
> > -Wmissing-declarations -Wmissing-prototypes -Wnested-externs
> > -Wpointer-arith -Wshadow -Wstrict-prototypes -Wwrite-strings 
> > -Winline --param max-inline-insns-single=100  -mllvm
> > -stack-alignment=8 -mllvm -inline-threshold=3  -mllvm
> > -enable-load-pre=false -ffreestanding -mpreferred-stack-boundary=2 
> > -mno-mmx -mno-3dnow -mno-sse -mno-sse2 -mno-sse3 -msoft-float
> > -std=gnu99    -S -o boot2.s.tmp
> > /usr/src/sys/boot/i386/boot2/boot2.c
> > sed -e '/align/d' -e '/nop/d' < boot2.s.tmp > boot2.s
> > rm -f boot2.s.tmp
> > clang  -c boot2.s
> > clang -Os  -fno-guess-branch-probability  -fomit-frame-pointer
> > -fno-unit-at-a-time  -mno-align-long-strings  -mrtd  -mregparm=3
> > -DUSE_XREAD  -DUFS1_AND_UFS2  -DFLAGS=0x80  -DSIOPRT=0x3f8
> > -DSIOFMT=0x3  -DSIOSPD=9600
> > -I/usr/src/sys/boot/i386/boot2/../../common
> > -I/usr/src/sys/boot/i386/boot2/../btx/lib -I.  -Wall
> > -Waggregate-return -Wbad-function-cast -Wcast-align
> > -Wmissing-declarations -Wmissing-prototypes -Wnested-externs
> > -Wpointer-arith -Wshadow -Wstrict-prototypes -Wwrite-strings 
> > -Winline --param max-inline-insns-single=100  -mllvm
> > -stack-alignment=8 -mllvm -inline-threshold=3  -mllvm
> > -enable-load-pre=false -ffreestanding -mpreferred-stack-boundary=2 
> > -mno-mmx -mno-3dnow -mno-sse -mno-sse2 -mno-sse3 -msoft-float
> > -std=gnu99     -c
> > /usr/src/sys/boot/i386/boot2/sio.S
> > ld -static -N --gc-sections -nostdlib -Ttext 0x2000 -o boot2.out
> > /usr/obj/usr/src/sys/boot/i386/boot2/../btx/lib/crt0.o boot2.o
> > sio.o objcopy -S -O binary boot2.out boot2.bin
> > btxld -v -E 0x2000 -f bin -b
> > /usr/obj/usr/src/sys/boot/i386/boot2/../btx/btx/btx -l boot2.ldr 
> > -o boot2.ld -P 1 boot2.bin
> > kernel: ver=1.02 size=690 load=9000 entry=9010 map=16M pgctl=1:1
> > client: fmt=bin size=15a1 text=0 data=0 bss=0 entry=0
> > output: fmt=bin size=1e31 text=200 data=1c31 org=0 entry=0
> > -49 bytes available
> > *** [boot2] Error code 1
> >
> > Stop in /usr/src/sys/boot/i386/boot2.
> > *** [all] Error code 1
> >
> > Stop in /usr/src/sys/boot/i386.
> > *** [all] Error code 1
> >
> > Stop in /usr/src/sys/boot.
> > *** [all] Error code 1
> >
> > Stop in /usr/src/sys.
> > *** [sys.all__D] Error code 1
> >
> > Stop in /usr/src.
> > *** [everything] Error code 1
> >
> > Stop in /usr/src.
> > *** [buildworld] Error code 1
> >
> > Stop in /usr/src.
> 
> Here is a patch to work around the problem:
> 
> http://people.freebsd.org/~jkim/boot2.diff
> 
> Please note this patch creates two separate boot codes, one for UFS1 
> and one for UFS2.  To generate previous boot code (i.e., UFS1+UFS2) 
> with GCC, clean objects, add the following line to 
> your /etc/make.conf, rebuild, and install:
> 
> BOOT2_UFS=UFS1_AND_UFS2

I would really rather not go this route.  That is going to cause a lot of pain 
and suffering for users.

-- 
John Baldwin