#2013: ghci crash on startup: R_X86_64_32S relocation out of range.
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Reporter: mboes | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 6.8.3
Component: GHCi | Version: 6.9
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Testcase: | Architecture: x86_64 (amd64)
Os: FreeBSD |
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Comment (by mboes):
Good news: I have a working ghci loading base and giving me a prompt! This
is done by adding MAP_FIXED to the EXTRA_MAP_FLAGS and giving a hint
address, both in loadObj() and in x64_64_high_symbol(). Of course, ghci
segfaults the minute you try to link in more packages, because new
objects will overwrite the old ones in memory at the fixed address.
The upshot is that forcing 32-bit clean mmap()'s is the only issue needing
solving for ghci on FreeBSD/amd64. All the bugs I used to see with 6.6.1
(eg. race conditions with writing characters to the screen) are now gone.
The trick to solve this issue is to calculate a valid place in memory to
mmap() objects in, large enough for the whole object, that does not
conflict with anything else living in memory. Simon, any suggestions as to
the best way to do that?
At the moment I'm loading the object at the 1Gb boundary, and looking
around on the web that's the way that Xorg project are working around
their need for a MAP_32BIT flag on NetBSD. It's an ugly hack, but I don't
see any other way of dealing with a lack of MAP_32BIT. We could increment
the load address by oc->fileSize + <space for jump islands> at each object
load, so that all objects are somewhere above the 1Gb mark. Then create
jump islands for each loaded object directly after it in memory. However,
if we're loading so much in memory at fixed locations we'd have to be very
sure that nothing else is allocated above the 1Gb mark before the linking.
How feasible is this?
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2013#comment:7>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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