Re: GCC8 v.s. amiga

[mlelstv%serpens.de@localhost (Michael van Elst)]

rokuyama.rk%gmail.com@localhost (Rin Okuyama) writes:

>Hi,

>On 2020/06/25 20:26, Michael van Elst wrote:
>> rokuyama.rk%gmail.com@localhost (Rin Okuyama) writes:
>> 
>>> kernels for sun3 and luna68k seem (almost) OK. Kernel for mac68k
>>> works if -fno-omit-frame-pointer is specified (-fomit-frame-pointer
>>> is enabled by default for optimize levels >= -O1 for GCC8).
>> 
>> Just tried a gcc8 compiled 9.99.68 kernel on an emulated 68040 Amiga.
>> No problems to see.

>Thank you very much for testing!

>Hmm, then it is problem peculiar to 68060, or GCC miscompile something
>with tuning for 68060. I observed the problem both for -m68060 and
>-m68020-60.

>Which compiler flag do you use? Do you use GENERIC? Then, it is
>compiled with -m68020-60 by arch/m68k/Makefile.cmachflags...


I use a mostly stripped down GENERIC, but no change to CPU flags.
So yes, it is built with -m68020-60.


>Or emulator accepts some kinds of instructions that do not work on
>real hardwares?

I don't think so. But it doesn't emulate caches and the TLB works
differently.


Saying that, after a few hours idling in multi-user, the system
paniced with an uvm_fault followed by an illegal instruction
trap. Neither looked real in DDB.

I'll have to retry this with a gcc7-built kernel, it could be
some other m68k instability introduced in -current.

-- 
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."