[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [MiNT] Some mintlib patches
I'd really like to know what the real problem is here, this just seems
like another bandage for a real problem.
For me I've actually reverted your original patch to crt0.S and I don't
see a problem. So it'd be worth finding out if you reverted the file
back to the original and find out why gcc is crashing (if it really
still does).
It's quite tricky. The problem appears when you have low TPA (let's say
1024 KB) and big stack (let's say 256/512 KB). In gcc compilation, in
some (hard to say if deterministic) cases some compiled binary would
like to say "Fatal memory bla bla" but instead of this crashes (trap
call wants to put some stuff on stack but stack is corrupted somehow).
If you remember my early posts about gcc4 compilation (unable to use -O2
with some big files), this is exactly the case -- gcc should never
crash, it should write Fatal error message. This is quote from my mail:
---
I'm not sure
exactly why but I think it has something to do with that value used as
initial (early) stack -- it's set as (p_hitpa & 0xfffffffe) where
p_hitpa should be upper boundary of free process memory + 1 byte.
I think one of the possible explanations (why program sometimes
crashed and sometimes shows the message) is there's something wrong
with that early stack -- for example, when p_hitpa = 0x2000, 0x2000 &
0xfffffffe = still 0x2000 and we're one byte beyond the allowed area.
However, I was too tired/lazy to track it into kernel (if it reaches
kernel syscall or it just crash in trap handler) so I'm not 100% sure
about it. But this changing behaviour (bus error vs message) occurs
when I add code/variables to C source -- i.e. BSS could get
bigger/smaller i.e. odd/even in length.
---
But I never actually went deeper than this speculation since I wanted to
see gcc4 so much :) So if you ask about reproducibility, install aranym,
easymint, unpack&patch gcc-4.2.3, configure/make bootstrap and you'll
see the crash.
Then don't change it so often :-)
Haha, when you need to experiment (like spotting bug above) you'll
welcome this ;)
--
MiKRO / Mystic Bytes
http://mikro.atari.org