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From Gregory Shimansky <gshiman...@apache.org>
Subject Re: [general] harmony launch failed on AMD Geode LX
Date Fri, 01 Feb 2008 20:19:43 GMT
On 1 февраля 2008 Egor Pasko wrote:
> On the 0x3DD day of Apache Harmony Mark Hindess wrote:
> > > > in place of sfence in vm/vmcore/src/thread/linux/atomics.cpp.
> > >
> > > Yes I think this should help on processors with no SSE (not to mention
> > > SSE2) support.
> >
> > It does.  HelloWorld runs okay with -Xint.  (Now I just need to find a
> > way to run the tests on a machine which boots to a small ramdisk from
> > compact flash and doesn't currently support network file systems.)
> >
> > Without -Xint, predictably, it fails with not-immediately-helpful core
> > which reports:
> >
> > (gdb) bt
> > #0  0xa649d24d in ?? ()
> > (gdb) x/1i $eip
> > 0xa649d24d:     (bad)
> >
> > It might be worth adding an option to the federation build compile for
> > a more limited processor so that people can do some testing w/-Xint - on
> > OLPC, Geode and VIA based machines?
>
> I tried to say that a build option would be nearly as hard to
> implement as a runtime option, which is more preferrable.

In class library I saw an interesting approach with code patching in assembly. 
It has a special segment with the same name (on windows all segments of the 
same name are merged across assembly sources) with labels for each LOCKed 
instruction. In case the system is determined to be uniprocessor, it patches 
all of the LOCK prefixes with NOP (see thrhelp.asm, thrspinlock.asm and 
lock386.c files).

In theory it could be possible to gather all of the locations of mfence, 
sfence, etc instructions in the code and patch them according to architecture 
at the initialization point. But in practice creating such a table is easy 
only for assembly.

-- 
Gregory

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