[uml-devel] Re: [uml-user] mem=64M, mem=128M, mem=ANYTHING ignored??

[Michael Roth <mroth@nessie.de>]

roland wrote:
> success, too.
> 
> the error definitely seems  to be a compile issue.
> if i compile with -O2, uml just uses the 32M memory default
> if i compile with -O1, uml uses the param "mem=..." the right way

I'm not sure and I'm to lazy to check this out, but IIRC I had the same 
problems using gcc-3.4.0.

> mhhh - don`t know how much "improvement" does "O2" in favour of "O1" - but
> who should we ask now, to help hunting this "bug" ?
> gcc folks ?

Maybe the gcc manual? RTFM? ;-)

http://gcc.gnu.org/onlinedocs/gcc-3.3.3/gcc/Optimize-Options.html

O1 Options:

-fdefer-pop  -fmerge-constants  -fthread-jumps  -floop-optimize 
-fcrossjumping  -fif-conversion  -fif-conversion2  -fdelayed-branch 
-fguess-branch-probability  -fcprop-registers

O2 Options (O1 options plus the following):

-fforce-mem  -foptimize-sibling-calls  -fstrength-reduce 
-fcse-follow-jumps  -fcse-skip-blocks  -frerun-cse-after-loop 
-frerun-loop-opt -fgcse  -fgcse-lm  -fgcse-sm 
-fdelete-null-pointer-checks  -fexpensive-optimizations  -fregmov 
-fschedule-insns  -fschedule-insns2  -fsched-interblock  -fsched-spec 
-fcaller-saves  -fpeephole2  -freorder-blocks  -freorder-functions 
-fstrict-aliasing  -falign-functions  -falign-jumps  -falign-loops 
-falign-labels

Note: First, gcc-3.4.0 is slighlty different. Second, if the problem 
states only with gcc-3.x (x>=1) and not with gcc-3.0.0 or gcc-2.x, then 
maybe the bug in uml is triggered by the opcode scheduler in the newer 
gcc. IIRC correctly, the scheduler changed somewhere in the gcc-3.x 
line. But as always, I'm not sure. ;-)


Michael Roth




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