On Tue, Oct 28, 2003 at 11:49:38AM -0500, Camm Maguire wrote: > Greetings, and thank you so much for your reply on this issue! > > Please let me preface the below with the statement that these are, of > course, my opinions only, and that there may well be issues of which > I'm unaware which may contraindicate my conclusions. > > Briefly, I think this is a bug in libc6 because: > > 1) It makes stable unexeced binary images, to my understanding, > impossible.
Unexecing has never, however, worked portably. I think emacs even moved away from it, though I'm not sure of that. > base, I cannot find it. I've had a helpful suggestion from a > reader of debian-ia64 that I should modify the gcl's unexec to dump > the portion of the descriptor table containing internal function > addresses into the image itself as a runtime override of ld.so's > work, but this appears both desperate and fragile. The alternatives are also desperate and fragile. That at least limits the damage to gcl. > 2) ld.so's changing of the function descriptor table is (apparently) > unnecessary, albeit possibly permitted by the ABI. To my > knowledge, the Debian port to hppa faced similar issues, yet the > implementation arrived at is free of this problem. In addition, > the same helpful respondent referred to above suggested three ways > in which this problem could be addressed at the ld.so level: The way that hppa does this is, I think, very different. Two of the suggestions below require substantial changes to the static linker and some fudging with the ABI. Using sbrk would probably not solve the issue at all. > 3) The ld.so ia64-specific behavior is clearly the root of the tree of > these problems, and is the logical place to address them all once > and for all. And, unless the ABI mandates that the descriptors > *must* change across runs, implementing the descriptor table > creation in a manner consistent with function addressing use on all > the other Debian platforms is bound to improve the consistency, > continuity, and robustness of the distro as a whole. To be more > precise, the alternative to an ld.so fix is for every program from > now on which ever uses unexec to put in and maintain lengthy ia64 > specific #ifdef'ed modifications. > > Anyway, these are just my thoughts. There is a flaw in your logic. It's not "the ABI mandates that the descriptors *must* change across runs" so much as "the ABI offers no opportunity to *ensure* that descriptors do not change across runs". If anything this is a problem with the ia64 linux ABI; take it up with them. It can not be solved contained in glibc. -- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
