Thanks Marc and Alex, Yes it was 0x4<<60, missed a zero. I didn't know about the virtual regions, I assumed it was flat 64-bit.
For now I am going with Alex's suggestion and forcing the mmap to happen at a lower memory address, starting at mmap_min_addr. The guest_base is then large, causing a wraparound. This way also the region bits won't be disregarded, but will make 8 contiguous regions giving a flat 64-bit space. I don't know which types of programs make use of different regions simultaneously, will probably have to think about it later, but for now this is good enough. ~Prashant On Tue, Jul 12, 2011 at 10:44 PM, "Marc Lörner" <loer...@gmx.de> wrote: > Hello Prashant, > first of all your "0x4<<64" is wrong it's "0x4<<60". > In Volume 2 of the IASDM page 2:46 you see that these three upper bits > correspond to the 8 virtual regions (here: region 2). > So maybe you can just disregard these bits and use the rest as new offset > to an faked guest_base that fits your needs (e.g. somewhere in your > process space)? > > Regards, > Marc > > >Hello, > > > >I am working on target-ia64, but am stuck during ia64 ELF loading. > > > >Referring to function "probe_guest_base()" in linux-user/elfload.c around > >line 1350, called from around line 1484 -- > > > >When the main binary is being mmap'd, the host address and guest address > >should ideally be the same. If they're not, a linear search is done by > >increasing the host_address by one page and trying the mmap again. The > >(positive) offset is then saved. > > >The problem occurs with ia64 binaries, which typically start at > >0x4000000000000000 (i.e 0x4<<64). At least on my x86_64 host machine, > >mmap'ing at this address fails. The real_address is of the order of > >0x8<<32. Needless to say, increasing host_address and trying again will > >never reach a lower address to map at. Further, I cannot make it relocate > >to a lower host address because the offset (guest_base) is an unsigned >int > and so the relocation can only happen by a positive offset. > > > >Because of this it is not possible to load any ELF binaries which start > >at such high memory addresses. I can tailor an elf binary to start at a > >lower base address, which might work for that specific case, but I >suspect > most existing ia64 binaries start at 0x4<<64 by convention. Also, >the > "hiaddr" is read from elf header which again is set to 0x4<<64 + some > >value. > > > >The existing code works fine with x86_64, for example, because the > >binaries are typically starting at 0x40000, which is easily mmap'd at > >first try. > > > >Any ideas on a workaround? > > > >~Prashant > -- > NEU: FreePhone - kostenlos mobil telefonieren! > Jetzt informieren: http://www.gmx.net/de/go/freephone >
