Update:
I was able to solve the problem.

The first useful step was to print all the instructions that ran on the
inorder CPU (--debug-flags=ExecAll helped here) and I found out that the
first instruction that caused problems was HW_REI.
Apparently, this instruction is not recognized as a control instruction by
the inorder CPU.

It looks like it is a known issue - see
http://www.mail-archive.com/[email protected]/msg02614.html - adding
"IsControl" to the hw_rei instruction (on /arch/alpha/isa/decoder.isa)
solves the problem and the inorder CPU successfully boots the Linux kernel.
This, however, also causes the O3 CPU to fail, so I'm currently keeping two
distinct versions for both CPUs.


Eyal Yaacoby


On Sat, Apr 28, 2012 at 3:42 AM, Eyal Yaacoby <[email protected]> wrote:

> Hi,
>
> I'm new to Gem5. I hope this is the right place to seek for help.
>
> I ran into a problem when trying to boot linux on Alpha full-system using
> an inorder CPU - after ~187 instructions, the CPU tries to read from
> address 0xfffff00188, gets an error (as it isn't translated properly), goes
> to sleep and never wakes up.
>
> This problem happens on both gem5 and gem5-stable, with two versions of
> "vmlinux" (the linux kernel alpha binary) I've tried, and with several
> different command lines, e.g.
> ./build/ALPHA_FS/gem5.debug  ./configs/example/fs.py --inorder --caches
> --l2cache
> ./build/ALPHA_FS/gem5.opt ./configs/example/fs.py --inorder --caches
> --l2cache
> and others.
> The same command lines work with all other CPU types.
>
> I've tried debugging it by outputting debug information, and I'm pretty
> sure something goes wrong earlier than that memory read (from
> 0xfffff00188), as I believe it should never get there, but I don't know
> where to look.
>
> Does the inorder CPU support booting the linux kernel on Alpha at all?
> Am I doing something wrong? If not, where can I look further to debug this
> issue?
>
> Thanks in advance,
> Eyal Yaacoby
>
>
>
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