Linux Kernel Network Subsystem Patching

Lennart Sorensen lsorense-1wCw9BSqJbv44Nm34jS7GywD8/FfD2ys at public.gmane.org
Tue Feb 4 19:21:48 UTC 2014


On Tue, Feb 04, 2014 at 11:51:24AM -0500, Kevin Cozens wrote:
> On 14-02-02 03:58 PM, Lennart Sorensen wrote:
> >
> >64bit is faster and a 64bit linux can run 32bit programs too (although
> >there are very few left you would have any reason to run as 32 bit).
> 
> Is it possible to run a system with only 64-bit libraries? I have
> stayed with 32-bit as I didn't have a ton of disk space for the root
> partition (until recently) so I didn't want to waste the space by
> having 32-bit and 64-bit versions of all libraries.

Sure you can have a 64bit only system.

And with Debian 7.0 (wheezy) as well as recent Ubuntu, they are multiarch
capable, which allows installing just the 32bit libraries and packages
you need.

You end up with things like this then:

lennartsorensen at lennartsorensen:~$ dpkg -l|grep libc6
ii  libc6:amd64                2.17-97     amd64     Embedded GNU C Library: Shared libraries
ii  libc6:i386                 2.17-97     i386      Embedded GNU C Library: Shared libraries
ii  libc6-dbg:amd64            2.17-97     amd64     Embedded GNU C Library: detached debugging symbols
ii  libc6-dev:amd64            2.17-97     amd64     Embedded GNU C Library: Development Libraries and Header Files
ii  libc6-dev-i386             2.17-97     amd64     Embedded GNU C Library: 32-bit development libraries for AMD64
ii  libc6-dev-x32              2.17-97     amd64     Embedded GNU C Library: X32 ABI Development Libraries for AMD64
ii  libc6-i386                 2.17-97     amd64     Embedded GNU C Library: 32-bit shared libraries for AMD64
ii  libc6-x32                  2.17-97     amd64     Embedded GNU C Library: X32 ABI Shared libraries for AMD64

So in this case I have libc6 for amd64, i386 and x32 (x32 is a new ABI).

x32 is pretty neat.  It does what a lot of other architectures have done
over the years (MIPS for example).  Essentially the idea is that since
x86_64 (aka amd64) added more registers and new useful instructions, but
uses twice as much memory for pointers, it would be nice to avoid the
memory overhead while keeping the register and instruction features.
So X32 is in fact x86_64 register and instruction set, with 32bit
pointers.  So all the benefits and none of the disadvantages.

MIPS did the same with old 32bit (for 32bit only chips and the original
instruction set), new 32bit (for 64bit chips but using 32bit pointers
but the new better instruction set), and 64bit.  powerpc and sparc systems
also generally use 32bit code in most casea and only use 64bit binaries
for the few cases where it makes sense, although there are plans to make
a pure 64bit powerpc linux architecture using little endian instead of
big endian.  It is probably primarily targeted at the super computing
users.

-- 
Len Sorensen
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