> On Sep 25, 2025, at 12:34 AM, Xi Ruoyao <[email protected]> wrote:
>
> On Thu, 2025-09-25 at 11:17 +0800, Huacai Chen wrote:
>> Hi, Ruoyao,
>>
>> On Tue, Sep 23, 2025 at 8:34 PM Xi Ruoyao <[email protected]> wrote:
>>>
>>> In some applications (notably the Linux kernel), "break 0" is used as a
>>> trap that a handler may be able to recover. But in GCC the "trap"
>>> pattern is meant to make the program rightfully die instead.
>>>
>>> As [1] describes, sometimes it's vital to distinguish between the two
>>> cases.
>>>
>>> Use the "documented illegal instruction" amswap.w $r0,$r1,$r0 for "trap"
>>> instead. This also aligns the behavior with x86_64 GCC and LoongArch
>>> clang.
>> Can we use "break 1" instead?
>
> AFAIK the break codes are allocated nowhere except in a Linux header so
> I don't want to use it in compiler which may target some different
> operating system.
Ideally the ABI would define this, but I don't know how many do. VAX/VMS comes
to mind as one that does (via the "BUGx" opcode).
paul
