kern/117591: [acpi][panic] Divide by zero bug in ACPI

[John Baldwin]

On Monday 19 November 2007 05:40:03 pm Jessica Mahoney wrote:
> The following reply was made to PR kern/117591; it has been noted by GNATS.
> 
> From: Jessica Mahoney <root at varusonline.com>
> To: John Baldwin <jhb at freebsd.org>, bug-followup at FreeBSD.org
> Cc:  
> Subject: Re: kern/117591: [acpi][panic] Divide by zero bug in ACPI
> Date: Mon, 19 Nov 2007 17:06:40 -0500
> 
>  John Baldwin wrote:
>  > Can you get a stack trace?
>  >
>  >   
>  Tracing pid 878 tid 100080 td 0xc3f26440
>  acpi_battery_get_battinfo(c3a27980,c3ee4d00,e51e1c60,c3ee4d00,0,...) at 
>  acpi_battery_get_battinfo+0x26f
>  acpi_battery_ioctl(c0a44203,c3ee4d00,0,c40ec880,e51e1c08,...) at 
>  acpi_battery_ioctl+0x14b
>  acpiioctl(c3a9e900,c0a44203,c3ee4d00,3,c3f26440,...) at acpiioctl_0xdd
>  devfs_ioctl_f(c3e35d80,c0a44203,c3ee4d00,c3ee5800,c3f26440,...) at 
>  devfs_ioctl_f+0xcb
>  kern_ioctl(c3f26440,3,c0a44203,c3ee4d00,1000a24,..._ at kern_ioctl+0x355
>  ioctl(c3f26440,e51e1cfc,c,c3f26440,e51e1d2c,...) at ioctl+0x134
>  syscall(e51e1d38) at syscall+0x345
>  Xint0x80_syscall() at Xint0x80_syscall+0x20
>  --- syscall (54, FreeBSD ELF32, ioctl), eip = 0x2815289b, esp = 
>  0xbfbfec3c, ebp = 0xbfbfed28 ---
>  
>  If there's anything else needed, please let me know and I shall provide.

You can try this:

Index: acpi_battery.c
===================================================================
RCS file: /usr/cvs/src/sys/dev/acpica/acpi_battery.c,v
retrieving revision 1.25
diff -u -r1.25 acpi_battery.c
--- acpi_battery.c      9 Oct 2007 07:51:46 -0000       1.25
+++ acpi_battery.c      19 Nov 2007 23:17:48 -0000
@@ -198,8 +198,10 @@
         */
        if (bif->units == ACPI_BIF_UNITS_MA && bif->dvol != 0) {
            bst[i].rate = (bst[i].rate * bif->dvol) / 1000;
+#if 0
            bst[i].cap = (bst[i].cap * bif->dvol) / 1000;
            bif->lfcap = (bif->lfcap * bif->dvol) / 1000;
+#endif
        }

        /* Calculate percent capacity remaining. */

I think the mA => mW scaling is resulting in lfcap becoming 0, but since
all we want is a ratio for 'cap' so we can generate a percentage, we don't 
actually need to scale this.

-- 
John Baldwin