Linux x32 Is Made Easier With Ubuntu 13.04

[phoronix]

Phoronix: Linux x32 Is Made Easier With Ubuntu 13.04

While there isn't yet a release yet of Ubuntu in the Linux x32 ABI flavor, some packages now found in Ubuntu 13.04 make it easier to setup this binary interface that brings some 64-bit advantages to the 32-bit world...

http://www.phoronix.com/vr.php?view=MTM1OTA

[dh04000]

Sounds cool Michael, excited to see the result.

[GreatEmerald]

binary interface that brings some 64-bit advantages to the 32-bit world.

No, that's the other way round. It brings some 32-bit advantages to the 64-bit world, if you want to use such a construct.

[Sonadow]

if programs are compiled as x32, which libraries will they link to? x86 libraries, or x64 libraries?

[V10lator]

if programs are compiled as x32, which libraries will they link to? x86 libraries, or x64 libraries?

None of them. They will link to x32 libraries.

[GreatEmerald]

Indeed, x32 is its own architecture in that regard.

[Veerappan]

None of them. They will link to x32 libraries.

So, the next question... what sort of compatibility in a multi-lib system can we expect?

The processor is 64-bit and is using the x86-64 instruction set, but with 32-bit pointers... so it's a bit of a hybrid.

Will we get the lowest-common-denominator (i.e. x86), or do we also get compatibility with 64-bit libraries/programs?

Or is x32 special and can only run x32 code?

[Delgarde]

Indeed, x32 is its own architecture in that regard.

Which is what puzzles me about why it's deemed necessary. As far as I can tell, its only advantage is that it gains some of the performance benefits of 64-bit hardware, without the extra memory use that comes from doubling the size of every pointer. That's not a big advantage, considering the hit you're taking from having to install duplicates of every library from glibc through to KDE/Gnome - and if you're actually running a mix of both x32 and x86_64, having to have both sets of libraries loaded into memory. Is anyone actually going to be coming out ahead by using this?

[elanthis]

No, that's the other way round. It brings some 32-bit advantages to the 64-bit world, if you want to use such a construct.

Most appropriate to say that it brings AMD64 advantages (more registers, newer instructions, new calling convention) to the 32-bit world that doesn't need or want the larger address space and pointer size.

[Ericg]

Which is what puzzles me about why it's deemed necessary. As far as I can tell, its only advantage is that it gains some of the performance benefits of 64-bit hardware, without the extra memory use that comes from doubling the size of every pointer. That's not a big advantage, considering the hit you're taking from having to install duplicates of every library from glibc through to KDE/Gnome - and if you're actually running a mix of both x32 and x86_64, having to have both sets of libraries loaded into memory. Is anyone actually going to be coming out ahead by using this?

Thats exactly what it does Delgarde, you get the performance benefits of the 64bit, without the memory implications. So say you've got a brand new CPU but only 1gig of memory (for whatever reason) x32 is your best option.