On Aug 22 09:22, Warren Young wrote: > If you try something like this from a Cygwin 64 install: > > $ /cygdrive/c/cygwin32/bin/ls > > you get an error like this: > > 3 [main] ls (8168) C:\cygwin32\bin\ls.exe: *** fatal error - > cygheap base mismatch detected - 0x0/0x612A0950. > > It goes on to explain that this is due to trying to load an > incompatible cygwin1.dll. > > My best guess is that this happens because the standard Windows DLL > search logic[1] says "oh, I already have a CYGWIN1 module loaded, I > will use that one." And boom. > > Yet, if that were truly what's going on, DLL redirection[2] should > fix it. From Cygwin 64 again: > > $ touch /cygdrive/c/cygwin32/bin/ls.exe.local > $ /cygdrive/c/cygwin32/bin/ls > same complaint as before > > Another oddity is that the inverse test succeeds. From Cygwin 32: > > $ /cygdrive/c/cygwin64/bin/ls > all my base > $ > > In another forum[3], Yaakov told me that Windows is supposed to be > taking CPU bitness into account here, which should be another way > for it to work without special help. I don't see mention of such a > rule in [1], however. > > What is really going on here? > > Understand, I'm not asking because I want it fixed. I mean, it'd be > *nice* if it were fixed, but I'm more interested in knowing why it > is the way it is.
When execveing a Cygwin process, a lot of data is submitted via shared memory, via data copying, and via a special parameter to the CreateProcess call with the mysterious name "lpReserved2". One problem is the differences in basic datatypes, which results in incompatible datastructures between 32 and 64 bit. While this could be worked around, this doesn't help for the shared memory stuff, which depends on the installation path of the cygwin DLL. The Cygwin DLL in C:\cygwin1 would use a different name for the shared mem regions than the Cygwin DLL installed into C:\cygwin2, independent of the target architecture. This is by design since Cygwin 1.7. One effect: No tty sharing. Therefore, interaction between the 32 and 64 bit DLLs is not supported. This was an early design goal when we discussed the 64 bit DLL on the cygwin-developers list two years ago, but I was almost the only one favoring this approach, AFAIR. It also turned out that the complexity of this approach was pretty high, so we discussed it again early 2013 and I dropped it, otherwise we would very likely not have a 64 bit distro at this time. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat
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