Re: AMD response about Debian x86-64 port
Bart Trojanowski <email@example.com> writes:
> I will assume that if we do any work we must start with a 64-bit kernel.
Patches available from ftp://ftp.x86-64.org/pub/linux-x86_64/
> From what I understand, the hardware provides a "64-bit long mode" in
> which the kernel could run and allow for 32-bit applications to execute
> without recompilation (this later mode is referred to as compatibility
> submode of long mode).
> However, recalling Andi Kleen's talk at OLS two years ago, I believe
> that a recompile will still be needed for these 32-bit apps due to
> an ABI change on the x86-64 platform.
ia32 apps work as-is, even binary-only stuff like the acrobat reader.
> There may be some apps that will (initially) not work in 64-bit
> mode, and for these we use 32-bit mode. The only snag with this is
> that we now need two glibc's on the system: the 32-bit one and the
> 64-bit one.
That biarch thing (i.e. have 64bit and 32bit apps happily coexist on
the system) is actually a non-trivial issue. One way to handle this
is to place 32bit shared libraries into $prefix/lib and the 64bit ones
into $prefix/lib64. SuSE does it this way, I think the toolchain
(gcc, binutils + friends) want it this way too. This has a number of
intresting consequences through:
* The package file lists are not fixed any more because libdir
depends on the build architecture. Plenty of packages likely must
be touched to deal with this.
* Maybe it is possible to simply reuse the i386 debs for the 32bit
personality. That likely requires some (probably non-trivial)
changes in dpkg and apt.
Gerd Knorr <firstname.lastname@example.org>