Re: (arm64) link_elf: symbol __floatundidf undefined ...

On 26 May 2025, at 15:05, Bjoern A. Zeeb <bzeeb-lists@lists.zabbadoz.net> wrote:
> 
> On Mon, 26 May 2025, Dimitry Andric wrote:
> 
> Hi,
> 
> thanks for the quick answer.
> 
>> On 26 May 2025, at 14:25, Bjoern A. Zeeb <bzeeb-lists@lists.zabbadoz.net> wrote:
>>> 
>>> I've just compiled and installed a new arm64/main with my own kernel
>>> config to have wifi bits as modules.
>>> 
>>> I am a bit puzzed as to where this comes from in the kernel.
>>> 
>>> # kldload wlan
>>> link_elf: symbol __floatundidf undefined: 0xffff000143ed1370 0xffff000143ecf9f0 11496 0xffff000143ed26d8 0x2
>>> kldload: can't load wlan: No such file or directory
>>> 
>>> % nm modules/usr/src/sys/modules/wlan/wlan.ko.full | grep float
>>>                U __floatundidf
>>> 
>>> Anyone any idea?
>> 
>> _Something_ is converting a unsigned long to a double, but what? Can you figure out which object file it is?
> 
> % nm ieee80211_ioctl.o | grep __floatundidf
>                 U __floatundidf
> 
> This may be a local change I have adding an extra 10% of space in the
> ioctl code to accomodate for enlargement of a result set for testing.
> size_t space;
> ...
> space *= 1.10;
> 
> Given it's likely that it's that I think the real question is, why is this
> not an issue on amd64 but on arm64 as I've been running that change for
> days on amd64?

My guess is that it's inlined on amd64. For me simple cases also inline on arm64, but maybe you are doing something more complicated:

$ cat convert.c
#include <stddef.h>

size_t f(size_t s)
{
  return s * 1.10;
}

$ cc -target aarch64-freebsd -S convert.c -o -
        .text
        .file   "convert.c"
        .section        .rodata.cst8,"aM",@progbits,8
        .p2align        3, 0x0                          // -- Begin function f
.LCPI0_0:
        .xword  0x3ff199999999999a              // double 1.1000000000000001
        .text
        .globl  f
        .p2align        2
        .type   f,@function
f:                                      // @f
        .cfi_startproc
// %bb.0:                               // %entry
        sub     sp, sp, #16
        .cfi_def_cfa_offset 16
        str     x0, [sp, #8]
        ldr     d0, [sp, #8]
        ucvtf   d0, d0
        adrp    x8, .LCPI0_0
        ldr     d1, [x8, :lo12:.LCPI0_0]
        fmul    d0, d0, d1
        fcvtzu  x0, d0
        add     sp, sp, #16
        .cfi_def_cfa_offset 0
        ret
.Lfunc_end0:
        .size   f, .Lfunc_end0-f
        .cfi_endproc
                                        // -- End function
        .ident  "FreeBSD clang version 19.1.7 (https://github.com/llvm/llvm-project.git llvmorg-19.1.7-0-gcd708029e0b2)"
        .section        ".note.GNU-stack","",@progbits
        .addrsig

-Dimitry