Re: port-sgimips/53519 (aoutboot is broken since old NetBSD release.)

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

The following reply was made to PR port-sgimips/53519; it has been noted by GNATS.

From: Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: nullnilaki%gmail.com@localhost, tsutsui%ceres.dti.ne.jp@localhost
Subject: Re: port-sgimips/53519 (aoutboot is broken since old NetBSD release.)
Date: Sun, 2 Sep 2018 20:22:35 +0900

 > Confirmed as objcopy issue. I'll note it later.
 
 The original ip2xboot from NetBSD 8.0 has the following sections:
 
 ---
 /s/src/obj.sgimips/tooldir.NetBSD-8.0-i386/bin/mipseb--netbsd-size -A ip2xboot.elf
 ip2xboot.elf  :
 section            size                   addr
 .text             46240   18446744071696293888
 .text.startup       828   18446744071696340128
 .rodata            4796   18446744071696340960
 .reginfo             24   18446744071696345756
 .MIPS.abiflags       24   18446744071696345784
 .data               336   18446744071696345808
 .sbss              1148   18446744071696346144
 .bss                640   18446744071696347296
 .pdr               5152                      0
 .gnu.attributes      16                      0
 .comment             33                      0
 .ident               62                      0
 Total             59299
 ---
 
 An aoutboot binary (actually ecoff binary) converted by objcopy(1) has
 the following sections:
 
 ---
 % /s/src/obj.sgimips/tooldir.NetBSD-8.0-i386/bin/mipseb--netbsd-size -A aoutboot-objcopy
 aoutboot-objcopy  :
 section     size         addr
 .text      46240   2281709568
 .text.st     828   2281755808
 .rodata     4800   2281756640
 .reginfo      24   2281761436
 .MIPS.ab      24   2281761464
 .data        336   2281761488
 .sbss       1148   2281761824
 .bss         640   2281762976
 .gnu.att      16            0
 Total      54056
 ---
 
 ARCBIOS loads this binary (and fails) as reported in the PR:
 
 ---
 >> bootp()aoutboot
 Setting $netaddr to 192.168.20.39 (from server mirage)
 Obtaining aoutboot from server mirage
 47068+5200   
 Exception: <vector=UTLB Miss>
 Status register: 0x30004803<CU1,CU0,IM7,IM4,IPL=???,MODE=KERNEL,EXL,IE>
 Cause register: 0x800c<CE=0,IP8,EXC=WMISS>
 Exception PC: 0x9fc3ddac, Exception RA: 0x9fc2a528
 exception, bad address: 0x0
 Local I/O interrupt register 0: 0x8 <ENET>
 Local I/O interrupt register 1: 0x80 <VR/GIO2>
   Saved user regs in hex (&gpda 0xa8740e48, &_regs 0xa8741048):
   arg: a8740000 4e657442 53442f73 ba00
   tmp: a8740000 64 a8743ed8 1450 1450 a87487e0 0 887feca0
   sve: a8740000 3 400000 8000000 16 3f80 0 c000000
   t8 a8740000 t9 0 at 0 v0 0 v1 0 k1 0
   gp a8740000 fp 0 sp 0 ra 0
 
 PANIC: Unexpected exception
 
 [Press reset or ENTER to restart.]
 ---
 
 "47068" seems:
   46240 (.text)
 + 828 (.text.startup).
 
 "5200" seems:
   4800 (.rodata)
 + 24 (.reginfo)
 + 24 (MIPS.abiflags)
 + 336 (.data)
 + alignment?
 
 There is no info about .bss.
 
 I removed the extra .gnu.attributes section (that has no valid address)
 by -R option then it went a bit further, but ARCBIOS still fails
 to execute it:
 
 ---
 aoutboot-objdump-no-gnu.attributes  :
 section     size         addr
 .text      46240   2281709568
 .text.st     828   2281755808
 .rodata     4800   2281756640
 .reginfo      24   2281761436
 .MIPS.ab      24   2281761464
 .data        336   2281761488
 .sbss       1148   2281761824
 .bss         640   2281762976
 Total      54040
 
 ---
 >> bootp()aoutboot
 Setting $netaddr to 192.168.20.39 (from server mirage)
 Obtaining aoutboot from server mirage
 47068+5184+1788 entry: 0x88002000
 g...
 g...
 
 Exception: <vector=UTLB Miss>
 Status register: 0x30004803<CU1,CU0,IM7,IM4,IPL=???,MODE=KERNEL,EXL,IE>
 Cause register: 0x8008<CE=0,IP8,EXC=RMISS>
 Exception PC: 0x880024b0, Exception RA: 0x8800d544
 exception, bad address: 0x0
 Local I/O interrupt register 1: 0x80 <VR/GIO2>
   Saved user regs in hex (&gpda 0xa8740e48, &_regs 0xa8741048):
   arg: a8740000 196 0 1
   tmp: a8740000 88010000 887fe894 88010000 7 ffffffff 76 88010000
   sve: a8740000 3 400000 8000000 16 3f80 0 c000000
   t8 a8740000 t9 0 at 0 v0 0 v1 0 k1 0
   gp a8740000 fp 0 sp 0 ra 0
 
 PANIC: Unexpected exception
 
 [Press reset or ENTER to restart.]
 ---
 
 The failed address 0x880024b0 is in getopt() and the exception is caused
 by a NULL pointer dereference, so I guess some data is not loaded correctly.
 
 An aoutboot binaryconverted by elf2ecoff(1) has the following
 simple sections:
 
 ---
 % /s/src/obj.sgimips/tooldir.NetBSD-8.0-i386/bin/mipseb--netbsd-size -A aoutboot-elf2ecoff
 aoutboot-elf2ecoff  :
 section    size         addr
 .text   52256   2281709568
 .data       0   2281761824
 .bss     1792   2281761824
             0            0
             0            0
             0            0
 Total   54048
 ---
 
 ARCBIOS loads this binary (and executes successfully) as the following:
 
 ---
 >> bootp()aoutboot
 Setting $netaddr to 192.168.20.39 (from server mirage)
 Obtaining aoutboot from server mirage
 52256+0+1792 entry: 0x88002000
 
 NetBSD/sgimips 8.0 Bootstrap, Revision 1.5 (Sat Sep  1 18:49:55 UTC 2018)
 
 devopen: scsi(0)disk(1)rdisk(0)partition(0) type scsi file /netbsd
 4908464+131360 [267552+259212]=0x54f6c4
 ---
 
 "52256" is .text. It seems merged from all sections except .sbss and .bss
 (for simplicity?):
   46240 (.text)
 + 828 (.text.startup)
 + 4800 (.rodata)
 + 24 (.reginfo)
 + 24 (MIPS.abiflags)
 + 336 (.data)
 + alignment?
 
 The next "0" means there is no .data section
 (because it's merged into .text).
 
 The last "1792" seems .sbss (1148) + .bss (640) + alignemnt.
 
 
 I wonder if we can deal these annoying sections in ldscript for objcopy,
 but I think it's much easier to use our traditional elf2ecoff,
 as pmax and luna68k (using elf2aout) etc. do.
 
 A bit off-topic, but probably NetBSD/arc has the same problem.
 At least, we have to remove the .gnu.attributes section in
 sys/arch/arc/stand/boot/Makefile.
 
 ---
 Izumi Tsutsui