I was trying to build a GCC cross compiler with a target of "i686-coff". It failed with "Error: Alignment not a power of 2"I found various references to this, e.g.http://sources.redhat.com/ml/crossgcc/2001-03/msg00176.html from Kai Ruottu <kai.ruottu@luukku.com>The fix given there was to add lines as follows to i386-coff.h: #undef ASM_OUTPUT_ALIGN#define ASM_OUTPUT_ALIGN(FILE,LOG) \ if ((LOG)!=0) fprintf ((FILE), "\t.align %d\n", 1<<(LOG))This worked.As this seems to be an old chestnut (it was already one in 2001) could the fix be added to the reference source, so that everyone making a cross-compiler doesn't have to patch? Subject: Re: New: Alignment error building gcc with i686-coff targetrichard dot parratt at netiq dot com wrote:> I was trying to build a GCC cross compiler with a target of "i686-coff". > It failed with "Error: Alignment not a power of 2"The problem here is that there is some historical confusion over whether the argument to the .align directive is the number of bytes or the log of the number of bytes. Gas changed a few times long ago, and eventually settled on using number of bytes for all x86 targets except aout and go32. The gcc i386-coff port defaults to using the log of the number of bytes, and hence conflicts with gas.Hoewver, if gcc is configured right, this shouldn't be a problem. gcc will find the cross assembler, gas, and do a test to determine how to emit assembler align directives. I know of at least 3 ways to get this right.1) Configure gcc and gas in a combined source tree.2) Configure, build, and install gas using the same prefix as is used for gcc, before configuring gcc.3) Use the --with-as= option when configuring gcc to point at the cross assembler.If you don't do one of these things, then gcc won't build correctly anyways, so you actually have to do something wrong to end up with this problem. I noticed that if I configured gcc wrong, and then configured it correctly, I ended up with this problem because bad data was read from the config.cache file produced by the first configure run.Anyways, this is easy enough to fix, so I will check in a patch for it. Fixed in mainline. Technically, this isn't a regression, so I don't think weneed it fixed in gcc-3.3 or gcc-3.4. Also, I supplied info on how to workaround the problem. Comment 5Mark Mitchell 2004-10-31 01:59:08 UTC Already fixed on mainline, will not be fixed in GCC 3.4.x. | |