[microblaze-uclinux] microblaze+MMU optimization issues

[Steven Hein <ssh@xxxxxxx>]

Hi John,

I've been trying to characterize what kind of performance
we'll see from our Microblaze+MMU design.   As part of this,
I've been trying to play with higher levels of optimization
in kernel and user packages.   I've noticed that I can't use
-O2 optimization in most user apps that use fork().  (I've
observed this with the busybox, sysvinit, and dropbear
packages).

I'm sure I need to provide more detail on this....but what
I have observed is when I fork() is called on an app compiled
with -O2, the child process has garbage in many of the
variables that it inherits from the parent.    When I run
with -O (or in some cases -Os), then everything works fine.
I haven't been able to reproduce the symptom with a simple
piece of test code at this point.    Is this behavior
something that you have seen?    (I see that most components
of the release are not built with -O2, but rather -Os).
If so, is it something that I can set -O2 and disable a
particular optimization?    Also, I saw a previous email
from you that said you were testing a new compiler/toolchain--
does this newer version resolve the problem?


Also.....are there any plans for being able to build
libraries that are optimized for a particular design
(i.e. with HW multiplication or division enabled)?
Is the source for the toolchains available  (i.e. to allow
them to be built via crosstool)?


Thanks,
Steve

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