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Re: Bypassing the 2/3/4GB virtual memory space on 32-bit ports

crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68

On Thu, Aug 8, 2019 at 9:39 PM Aurelien Jarno <aurelien@aurel32.net> wrote:

> We are at a point were we should probably look for a real solution
> instead of relying on tricks.

 *sigh* i _have_ been pointing out for several years now that this is
a situation that is going to get increasingly worse and worse, leaving
perfectly good hardware only fit for landfill.

 i spoke to Dr Stallman about the lack of progress here:

he expressed some puzzlement as the original binutils algorithm was
perfectly well capable of handling linking with far less resident
memory than was available at the time - and did *NOT*, just like gcc -
assume that virtual memory was "the way to go".  this because the
algorithm used in ld was written at a time when virtual memory was far
from adequate.

 then somewhere in the mid-90s, someone went "4GB is enough for
anybody" and ripped the design to shreds, making the deeply flawed and
short-sighted assumption that application linking would remain -
forever - below 640k^H^H^H^H4GB.

 now we're paying the price.

 the binutils-gold algorithm (with options listed in the bugreport, a
is *supposed* to fix this, however the ld-torture test that i created
shows that the binutils-gold algorithm is *also* flawed: it probably
uses mmap when it is in *no way* supposed to.

 binutils with the --no-keep-memory option actually does far better
than binutils-gold... in most circumstances.  however it also
spuriously fails with inexplicable errors.

 basically, somebody needs to actually properly take responsibility
for this and get it fixed.  the pressure will then be off: linking
will take longer *but at least it will complete*.

 i've written the ld-torture program - a random function generator -
so that it can be used to easily generate large numbers of massive c
source files that will hit well over the 4GB limit at link time.  so
it's easily reproducible.


p.s. no, going into virtual memory is not acceptable.  the
cross-referencing instantly creates a swap-thrash scenario, that will
put all and any builds into 10 to 100x the completion time.  any link
that goes into "thrash" will take 2-3 days to complete instead of an
hour.  "--no-keep-memory" is supposed to fix that, but it is *NOT* an
option on binutils-gold, it is *ONLY* available on the *original*

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