Program section alignment on MIPS

Program section alignment on MIPS

[Paul Koning]

I've noticed a change between binutils 2.17 and older versions (2.14
at least; don't know for sure when this arrived).  In 2.14, the
program sections were aligned 2**12, which make sense given the MIPS
page size.  In 2.17 they are aligned 2**16, which I don't want and is
causing trouble.  

The biggest problem is that I can't find out where this number comes
from, nor how to change it.  Looking through the docs for "align"
turns up assorted things, but none that seem relevant and none that
help.

	paul

Re: Program section alignment on MIPS

[Mike Frysinger]

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On Monday 26 March 2007, Paul Koning wrote:
> I've noticed a change between binutils 2.17 and older versions (2.14
> at least; don't know for sure when this arrived).  In 2.14, the
> program sections were aligned 2**12, which make sense given the MIPS
> page size.  In 2.17 they are aligned 2**16, which I don't want and is
> causing trouble.

search the archives ... this comes up from time to time

> The biggest problem is that I can't find out where this number comes
> from, nor how to change it.  Looking through the docs for "align"
> turns up assorted things, but none that seem relevant and none that
> help.

look at the ELF_MAXPAGESIZE defines in the bfd/*elf*mips* files ... for 2.17, 
you'll need to change the define by hand:
http://uclibc.org/cgi-bin/viewcvs.cgi/trunk/buildroot/toolchain/binutils/2.17/400-mips-ELF_MAXPAGESIZE-4K.patch?rev=15498&view=auto

in latest binutils, there's a new ld option so you can change it on the 
fly ... -z max-page-size and -z common-page-size
-mike

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Re: Program section alignment on MIPS

[Thiemo Seufer]

Paul Koning wrote:
> I've noticed a change between binutils 2.17 and older versions (2.14
> at least; don't know for sure when this arrived).  In 2.14, the
> program sections were aligned 2**12, which make sense given the MIPS
> page size.  In 2.17 they are aligned 2**16, which I don't want and is
> causing trouble.  

The architecture allows variable page sizes between 1 k and 256 MB (not
all of them need to be implemented in a specific CPU). Some MIPS-based
machines use now 16 k pages for Linux. 64 k is a reasonable upper bound
for the default value, it is overridable via -z max-page-size /
-z common-page-size.

> The biggest problem is that I can't find out where this number comes
> from, nor how to change it.  Looking through the docs for "align"
> turns up assorted things, but none that seem relevant and none that
> help.

Grep for MAXPAGESIZE.


Thiemo