Bug 270534 - i386 13.1-RELEASE install CD: BTX halted: int=00000006 err=00000000 efl=00010006 eip=01405b81
Summary: i386 13.1-RELEASE install CD: BTX halted: int=00000006 err=00000000 efl=00010...
Status: Open
Alias: None
Product: Base System
Classification: Unclassified
Component: kern (show other bugs)
Version: 13.1-RELEASE
Hardware: i386 Any
: --- Affects Only Me
Assignee: freebsd-bugs (Nobody)
URL:
Keywords: install, needs-qa
Depends on:
Blocks:
 
Reported: 2023-03-30 04:47 UTC by Tim McIntosh
Modified: 2023-11-09 08:40 UTC (History)
3 users (show)

See Also:

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Description Tim McIntosh 2023-03-30 04:47:38 UTC 
When booting 13.1-RELEASE install CD, boot process stops with:

```
Loading kernel..
/boot/kernel/kernel text=Oxfc084 text=0xb39210 text=0x5b5100 data=0xb0 data=0x109290+0x2d5540 syms=[0×4+0xe91c0+0x4+8x17caac]
Loading configured modules.
can't find '/boot/entropy'
can't find "/etc/hostid'

int=00000006 err=00000000 efl=00010006 eip=01405b81
eax=02031444 ebx=000837b4 ecx=00000000 edx=02150bed
esi=01dcb7d0 edi=019ef0c8 ebp=019ef038 esp=00000000
cs=0008 ds=0010 es=0010 fs=0010 gs=0010 ss=0010
cs:eip=0f 45 f0 a1 88 f0 9e 01-85 c0 0f 45 f0 81 c6 ff
       ff 3f 00 81 e6 00 00 cO-ff 89 35 d4 a1 dc 01 8d
ss:esp=f0 7d 00 f0 f0 7d 00 f0-c3 e2 00 f0 f0 7d 00 f0
       f0 7d 00 f0 54 ff 00 f0-79 ea 00 f0 21 ea 00 f0
BTX halted
```

System is the one from bug #270495:

- Supermicro P5STE motherboard (Intel 430HX) <https://theretroweb.com/motherboards/s/supermicro-p5ste>
- Pentium 90? CPU
- 128MB RAM
- Builtin dual-IDE:
  - IDE0
    - primary: 1GB WDC disk
    - secondary: Toshiba XM6202B CDROM drive
  - IDE1
    - primary: 2GB WDC disk
    - secondary: N/A
- Adaptec AHA-2940 SCSI controller (ID 0)
  - ID 6 - 1GB SEAGATE disk
Comment 1 Tim McIntosh 2023-03-30 04:47:59 UTC 
This appears to be 100% repeatable.
Comment 2 Tim McIntosh 2023-03-30 04:51:17 UTC 
Is `int=00000006` an invalid opcode exception? I'm not familiar with interpreting x86 register dumps.
Comment 3 Tim McIntosh 2023-03-30 08:15:39 UTC 
Note: I just tried 11.4-RELEASE and hit the exact same exception after `Booting...`
Comment 4 Chuck Coffing 2023-11-05 23:24:37 UTC 
I just encountered this same "BTX halted" with the same cs:eip instruction stream, on an AMD K6-III booting FreeBSD 13.2 i386 bootonly iso.

The documentation at https://www.freebsd.org/platforms/i386/ claims that the i386 port will run on any i486 and newer.  However, notice the instruction stream:

cs:eip=0f 45

0f 45 is CMOVNE.  The CMOV instructions were introduced with the Pentium Pro.  The original reporter's P5 90 and my K6-III are both i586-class and do not support these i686 instructions.

I would expect that the BTX should be built using conservative instruction set, and more sophisticated CPU identification is done later in the boot.  So my guess is that BTX is being built wrong (for example, maybe no "-mtune").
Comment 5 Philipp Thiel 2023-11-09 08:40:17 UTC 
I have the same problem on an AMD K6-2. Probably compiler architecture is set to i686, i.e. Pentium Pro minimum.