[fpc-devel] Re: fpc build problems on some debian armel buildds

Mark Morgan Lloyd markMLl.fpc-devel at telemetry.co.uk
Thu Jun 30 18:24:01 CEST 2011

Riku Voipio wrote:
> On Thu, Jun 30, 2011 at 03:33:36PM +0100, peter green wrote:
>> The current FPC package builds fine in qemu for me. I will attempt to  
>> try on some real hardware too when I get a chance.
> Qemu allows unaligned memory accesses, which do not always work on real
> hardware, especially on armv5 and other older arms.
>> Is there a list anywhere of what hardware the buildds run on and/or any  
>> other interesting information about their setups so I can try to figure  
>> out what if anything the failing buildds have in common. Has anything  
>> changed in ancina's configuration recently?
> All currently running armel buildd's are identical marvell mv78x00 boards. 
> Updates on ancina are the regular "apt-get upgrades" to get latest toolchain
> etc in sid.

There were issues with some versions of FPC, related to more than a 
certain number of parameters (four?) being passed. Jonas wrote the 
following on the 5th October last year:

On 05 Oct 2010, at 10:05, Mark Morgan Lloyd wrote:

 > When running 2.4.0 on an ARM system (Debian v5 "Lenny", armel) with
 > limited memory (32Mb RAM + 768Mb swap) and using it to compile a large
 > project (Lazarus I'm seeing intermittent failures which go
 > away if the make is restarted. I've not seen this running on other
 > platforms, and I don't believe it is a problem in the Lazarus sources
 > since the build will eventually complete giving me runnable code.

A couple of days ago I fixed an error in svn trunk for ARMEL that caused 
the stack to become temporarily unbalanced after performing syscalls 
with 5 or more parameters (the bug is still there for OABI, but I can't 
fix that because I don't have access to an OABI machine).

A side-effect of that bug was that if the caller passed the address of 
its own result as one of the parameters to the system call, it would 
afterwards return a random value as its result and checks for error 
results caused random failures like the one you posted (the reproducible 
case that allowed me to fix it was a similar error).


There might be alignment issues on ARM and SPARC but I've only seen 
those with Lazarus, not with FPC itself.

Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]

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