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Re: [PLUG] RedHat 7.1 glibc2.1 Backward compat - revisited
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On Thu, May 24, 2001 at 12:45:28PM -0400, William Shank wrote:
> align bits properly?
>
Yes.
> i don't recall learning about that in my computer design and architecture
> classes?
>
Did they teach you assembler? If so, what chips? And what applications did
you write? Have you ever written a program that only used native linux
system calls and had absolutely no ties to libc? Obviously such a program
is completely non-portable....
> is that for real? if so, please point me to somewhere I can read up on bit
> alignment in the kernel.
>
http://www.ececs.uc.edu/~rreilova/linux/lkml-faq.html
Section 6, question 8 touches on it. See the archives for discussions.
http://www.goof.com/pcg/pgcc-faq.html#fpu
This touches on what happens when you compile an application aligned one
way, and DONT recompile a shared library with the same alignment. At least
with pgcc.
Short answer: it breaks.
> it sounds fishy to me.
why? whats to motive to make stuff like this up?
Just because you dont know something, doesnt mean it doesnt exist.
I'd be suprised if schools spent lots of time explaining microprocessors
and assembly language. Then again, I dont have a degree so what would I
know really? From what I've seen of many people who went to college for
computers... they pretty much try and cram in C/C++ and Java. The current
technologys. THe stuff you'll need to be employable. Then again, it really
depends on what you want to learn. Some stuff just isnt useful or
practical. See my above program that doesnt use libc. Besides geekyness,
who cares?
The main reason you've never heard of this so much is because its the
compilers job to do this. Sure, we could all be men and use punch cards,
or manually manipulate the inodes on the disk with a magnet, but I'm lazy.
I'd much rather let gcc worry about byte boundaries and alignment. So
would lots of other lazy people. Thats what the -m switches are for in gcc
:)
The entire point is to NOT have to write to the metal. THe issues about
RH, gcc and sunspots bores me to death. Its all on lkml, in all of its
anal retentive glory.
If you're really, really bored you can see the complete Execute and
Linkable Format (ELF) defined here:
http://www.muppetlabs.com/~breadbox/software/ELF.txt
Great stuff. All you ever wanted to know about symbol tables, but didnt
care about.
--
Mental
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