On 2016-06-23 04:30, John Paul Adrian Glaubitz wrote:
On 06/23/2016 07:54 AM, Alex McWhirter wrote:
I spend most of my time working on pure 64 bit sparc linux. simply
because that's where all the work is currently being done. That being
said there are
noticeable speed improvements with some applications being 32 bit.
Where did I say that it is impossible to run 32-bit applications? I
never claimed that!
I never claimed that either. The point was that i work on 64 bit because
it's what being actively developed / need implemented if linux for sparc
want to have a future.
As far as I know Debian doesn't really have a way of managing
something like that.Sure you can compile everything both 64 and 32 bit
and install whichever you
want, but there's no way to really say one package should always be 32
bit while another should always be 64 bit. Even if that did exist
sparc is the only
architecture I'm aware of that would really benefit from it.
Except that Debian has the best mechanism to resolve that which is
called Multi-Arch. You can install libraries
and binaries of *any* architecture onto *any* machine. In fact, I am
doing that to cross-compile things like
GHC, see:
https://wiki.debian.org/DebianPorts/BootstrappingGHC
Again, you're missing the point i was trying to make. A default install
of Solaris includes a mix of 32 bit / 64 bit binaries depending on what
the applications needs are. I can't think of any Linux distro that does
that. Using Debian amd64 as an example, you get a full 64 bit system
until you add i386 as an arch and install what you need as i386
binaries.
There is no way that i know of (short of doing it all by hand) to build
a single repository that has 32 bit applications / libs for some things
and 64 bit applications for others. Short of building such to tool, the
only option is to have a full 64 bit or full 32 bit userland and allow
the end user to use a different ABI per application if they wish.
If you build two repositories (one 32 bit and one 64 bit), there is no
easy way to prefer 32 bit packages for some things and 64 bit packages
for others. You can easily prefer entire repositories, but not each
package within those repositories.
The point isn't whether you can install packages for both ABI's. The
point is that there is no current way to have a mixed 32 bit / 64 bit
userland by default that is optimized based on a applications needs. Not
without doing a ton of work by hand.
My unofficial Gentoo ports support multilib for people wanting the
best of both worlds. But making it a seemless experience providing the
best performance based
on each applications needs is something that would take a ton of work.
It may not even be possible with the current packaging system.
Multilib alone is an outdated and insufficient concept and the reason
why we long had ugly solutions like ia32-libs
in Debian which carried 32-bit versions of important libraries
repackaged as 64-bit packages. These days, this has
become completely redundant since you can just directly install i386
packages on an amd64 system if you need 32-bit
support on x86_64, for example.
Debian's idea of multilib != Gentoo's idea of multilib. This is mostly
because Gentoo doesn't distribute binaries (except in very rare cases).
Gentoo may have similar issues, but because all package are built from
source i can just add "ABI=sparc32" to each package that doesn't need 64
bit support.
However, it doesn't end there. You can even go further and install
i386 packages on a ppc64el machine and run them
seemlessly there through qemu-user. Although we are currently missing
up-to-date 32-bit sparc packages which you
could install on sparc64 via MultiArch (unless you want to use the old
ones), there is nothing that stops you from
setting up a small mini-dinstall server, set up an sbuild schroot for
sparc and build custom packages for sparc
instead of sparc64.
Gentoo offers the same, but again the solutions they offer aren't as
robust because they don't have to deal with the whole binary package
aspect. One repo is good for all archs.
Thanks to the Debian rebootstrap project [1], we are constantly making
sure that bootstrapping sparc on Debian will
still be possible if required. The project is still under development,
but it's already possible to just cross-
bootstrap sparc with current packages on any host architecture.
Thus, I don't think any of the objections brought up against the
sparc64 port are valid. Neither is sparc64 64-bit
only nor does anyone anyhow prevent you in Debian to mix packages from
different architectures. In fact, Debian
has by far the most flexible approach to resolve the 32-bit/64-bit
problem by providing a generic approach for
mixing libraries of different architectures.
Adrian
[1] https://jenkins.debian.net/view/rebootstrap/
This wasn't supposed to be a "64 bit vs 32 bit vs debian vs gentoo"
post... I really don't care what other people run, you should just run
what you want.
I was just trying to make a few simple points...
1. Oracle knows sparc32 is faster than sparc64, that's why nearly half
of Solaris is 32 bit.
2. No Linux distribution has a solution in place for a default mixed
userland based on application optimization.
3. While sparc32 maybe more efficient, it would be a ton of work to go
through the entire repository to figure out which applications should be
compiled as sparc64 by default. vice versa, going through a sparc64
repository to figure out which applications should be compiled as
sparc32 by default would probably be even more work.
4. A sparc64 userland is safer than a sparc32 userland as you can
guarantee that all applications that need more than 4GB of memory will
get it, even if applications that don't need it receive a small
performance penalty. A sparc32 userland would deny additional memory to
those applications unless someone has curated the ABI assignment for the
entire repository or the user installs the sparc64 ABI version. When it
comes to "just working", the former is likely preferred.
As a side note, I've had this discussion many times before and the idea
of GCC optimizing sparc code to ilp32 when possible is probably the best
idea i've seen brought up. Maybe one day...
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