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Diffstat (limited to 'open_issues/glibc_init_first.mdwn')
| -rw-r--r-- | open_issues/glibc_init_first.mdwn | 78 |
1 files changed, 0 insertions, 78 deletions
diff --git a/open_issues/glibc_init_first.mdwn b/open_issues/glibc_init_first.mdwn deleted file mode 100644 index 774b7828..00000000 --- a/open_issues/glibc_init_first.mdwn +++ /dev/null @@ -1,78 +0,0 @@ -[[!meta copyright="Copyright © 2011 Free Software Foundation, Inc."]] - -[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable -id="license" text="Permission is granted to copy, distribute and/or modify this -document under the terms of the GNU Free Documentation License, Version 1.2 or -any later version published by the Free Software Foundation; with no Invariant -Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license -is included in the section entitled [[GNU Free Documentation -License|/fdl]]."]]"""]] - -[[!tag open_issue_glibc]] - -IRC, freenode, #hurd, 2011-07-22 - - [additional init-first.c patch] - < tschwinge> civodul: The only thing I wonder about: Roland also once had - done similar changes, which I then found they didn'T work with GCC 4.1, - and backed them out in 08f53ee9d265ffdc7e0affd6acf346cceeb65559 and fixed - the issue differently in d8d27e633a7860b37fd2e3142822b640a066cc0f (and - e17cef66140d4c97710ea88bd8d12612799e1e0f). Have you reviewed this? - < tschwinge> That's in the Savannah glibc repository. - < tschwinge> And this has been in 2007, four years ago. I don't remember - all the details. - < tschwinge> And here is quite a good summary of this stuff, from - init-first.c: - < tschwinge> /* XXX This is all a crock and I am not happy with it. - < tschwinge> This poorly-named function is called by static-start.S, - < civodul> braunr: thanks; i must admit it took me a while to figure it out - ;-) - < tschwinge> which should not exist at all. */ - < tschwinge> civodul: I can imagine... :-/ - < civodul> tschwinge: re Roland's changes, that's weird; i plan to try to - reinstate his change and see if it works - < civodul> now, i won't test with GCC 4.1... - < tschwinge> Yeah... - < tschwinge> I'm happy if it works with 4.4 onwards. - < tschwinge> civodul: And it's safe (in GCC terms) to write to ``* ((void - **) __builtin_frame_address (0) + 1)'', and similar? - < tschwinge> Or should we be coding this few stuff in assembly? - < civodul> tschwinge: well, we should add a compile-time assertion for - __builtin_return_address (0) == *((void**)__builtin_frame_address (0) + - 1) - < civodul> (i think GCC can figure it out at compile-time) - < civodul> but on IA32 it should always be true - < civodul> what's the name of glibc's compile-time assert macro already? - < tschwinge> I wonder whether that might interfere with some of GCC's - optimizations? - < civodul> what? - < tschwinge> Well, it seems unclean for me to be modifying a function's - return address from within C code. - < tschwinge> civodul: I added a verify.h in the t/verify.h branch. But - people didn't really like it too much. They rather wanted to directly - inline the array[(cond)?1:-1] code. - < civodul> ok - < civodul> i remember a debate about Gnulib's verify.h - < civodul> i thought something comparable had landed eventually - < tschwinge> civodul: Oh, maybe I missed it. - < tschwinge> civodul: In init-first.c:init, what about the usage of - data[-1] in the else path (not using cthreads) -- is that good as-is? - < civodul> tschwinge: oooh, it probably needs to fixed too - < civodul> but i haven't reached that point yet ;-) - * civodul tries to cross-bootstrap GNU from scratch - < tschwinge> civodul: I'd be happy to learn what was wrong with Roland's - original idea of fixing this. Or perhaps this was a GCC 4.1 bug? Or - perhaps GCC was inlining to much, and then got confused with frames and - return addresses? - < civodul> tschwinge: Roland's change looks good to me, so it could have - been a GCC bug - < civodul> tschwinge: OK to commit the patch to t/init-first.c (with both - data[-1] replaced)? - < tschwinge> civodul: OK, if you are confident that it works with GCC 4.4 - onwards. If yes, please add your changelog snippet to .topmsg, and also - add a not that Roland's original code may in fact have been fine, and we - may have hit a compiler bug. - < civodul> tschwinge: OK, will do - < civodul> tschwinge: though regarding Roland's change, i'd prefer to - actually test and see - < tschwinge> civodul: Thanks! |