openboot question

openboot question

[Kapil Chowksey]

I am trying to debug the ultralinux kernel (sparc64 using prom ver
3.0). After doing a dload, I try to disassemble, but it just shows a
bunch of illtraps.

ok 4000 dload /tftpboot/vmlinux.aout

ok 404000 dis
<Shows a bunch of illtrap instructions>

ok 404000 map?
<shows PADDR = 404000>

Is the `map?' command using dTLB entries ? How can I see which
Physical Addr does the vaddr 404000 map to in the iTLB ?

Also, setting a breakpoint to 404000 has no effect.

I would be grateful if someone can explain how to read the iTLB
mappings to specify the correct physical address in the `dis' command.

-- 
Kapil Chowksey                         Viva GNU !
kchowksey@hss.hns.com

Re: openboot question

[Eiki Ito]

Hi Kapil,

>I am trying to debug the ultralinux kernel (sparc64 using prom ver
>3.0). After doing a dload, I try to disassemble, but it just shows a
>bunch of illtraps.

I have seen the same problem.  Looks like 'dis' doesn't work until
you do a 'go'.  So you have to set a breakpoint somewhere first,
go, and then dis.

>Also, setting a breakpoint to 404000 has no effect.

I have seen this too.  Try breakpointing some other locations
(Look into head.S, avoid branches and try to find straight line
fetch parts).  This worked for me in most cases.  (I have no idea
why -- call Sun's customer support for explanation)

>Is the `map?' command using dTLB entries ? How can I see which
>Physical Addr does the vaddr 404000 map to in the iTLB ?

I haven't used 'map?' myself, but I believe map? reads the translation
table in main memory, not TLBs.  If you really need the contents of
TLBs, you can use ASI's (spacex@ etc).
But anyway, I think VA:404000 should map to PA:404000.

Thanks,
Eiki

Re: openboot question

[Jakub Jelinek]

> >Is the `map?' command using dTLB entries ? How can I see which
> >Physical Addr does the vaddr 404000 map to in the iTLB ?
> 
> I haven't used 'map?' myself, but I believe map? reads the translation
> table in main memory, not TLBs.  If you really need the contents of
> TLBs, you can use ASI's (spacex@ etc).
> But anyway, I think VA:404000 should map to PA:404000.

map? reads translations PROM knows about, and as we don't know exactly how
to tell PROM about our translations, map? simply does not work after head.S
code relocates the kernel and even more after we install our own trap table
with VPTE tricks etc.
VA 404000 should probably map to 4000 PA (if you fill your memory banks
from 0) or at the lowest physical address + 4000 in your system.
The nucleus virtual space looks like this:

0-4M: unmapped
4M-8M: kernel code+data
then modules, below 4G PROM mappings
then DVMA
fffff80000000000-fffffffc00000000 VA=PA+fffff80000000000
fffffffc00000000-ffffffffffffffff nucleus VPTE

Cheers,
    Jakub
___________________________________________________________________
Jakub Jelinek | jj@sunsite.mff.cuni.cz | http://sunsite.mff.cuni.cz
Administrator of SunSITE Czech Republic, MFF, Charles University
___________________________________________________________________
Ultralinux - first 64bit OS to take full power of the UltraSparc
Linux version 2.1.107 on a sparc64 machine (498.80 BogoMips).
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