[ECOS] arm gdb stub: user / supervisor mode

[ECOS] arm gdb stub: user / supervisor mode

[Fabrice Gautier]

Hi,

Can I use the redboot gdb stub safely with program that go back and forth
between user and supervisor mode? 
The first thing is that I'm think i always get the supervisor mode registers
in gdb. Is there any support for accessing the banked registers in gdb and
stubs?

What iam actually doing is debugging uClinux kernel on top of redboot. I has
to modify the uClinux kernel so that it doesnt install all the hardware
exception vectors (only irq and swi) and so far that worked pretty well but
now i'm wondering if the problem im seeing is in relation with the fact that
linux switch from svc to user mode

Thanks

-- 
Fabrice Gautier, 
Fabrice_Gautier@sdesigns.com

-- 
Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
and search the list archive: http://sources.redhat.com/ml/ecos-discuss

Re: [ECOS] arm gdb stub: user / supervisor mode

[Jonathan Larmour]

Fabrice Gautier wrote:
> 
> Hi,
> 
> Can I use the redboot gdb stub safely with program that go back and forth
> between user and supervisor mode?
> The first thing is that I'm think i always get the supervisor mode registers
> in gdb. Is there any support for accessing the banked registers in gdb and
> stubs?
> 
> What iam actually doing is debugging uClinux kernel on top of redboot. I has
> to modify the uClinux kernel so that it doesnt install all the hardware
> exception vectors (only irq and swi) and so far that worked pretty well but
> now i'm wondering if the problem im seeing is in relation with the fact that
> linux switch from svc to user mode

The eCos ARM GDB support hasn't been designed to debug user mode, only svc
mode so you're breaking new ground here!

Sounds interesting. If you get it to work fully, let us know!

Jifl
-- 
Red Hat, Rustat House, Clifton Road, Cambridge, UK. Tel: +44 (1223) 271062
Maybe this world is another planet's Hell -Aldous Huxley || Opinions==mine

-- 
Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
and search the list archive: http://sources.redhat.com/ml/ecos-discuss

Re: [ECOS] arm gdb stub: user / supervisor mode

[Jonathan Larmour]

[-- Attachment #1: Type: text/plain, Size: 848 bytes --]

Jonathan Larmour wrote:
> 
> The eCos ARM GDB support hasn't been designed to debug user mode, only svc
> mode so you're breaking new ground here!

Actually it's been pointed out (by Mark S) that the current version of
vectors.S in our internal repository may handle this better. It doesn't
support user mode debugging, but it does support debugging of the other
privileged modes better than the current anoncvs version anyway, thanks to
a recent overhaul. To support user mode debugging probably involves forking
the exception handling into two paths early in the exception process. One
way for user mode being interrupted and the other is the current handling.

I've attached it anyway.

Jifl
-- 
Red Hat, Rustat House, Clifton Road, Cambridge, UK. Tel: +44 (1223) 271062
Maybe this world is another planet's Hell -Aldous Huxley || Opinions==mine

[-- Attachment #2: vectors.S.gz --]
[-- Type: application/x-gzip, Size: 8199 bytes --]

[-- Attachment #3: Type: text/plain, Size: 146 bytes --]

-- 
Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
and search the list archive: http://sources.redhat.com/ml/ecos-discuss

Re: [ECOS] arm gdb stub: user / supervisor mode

[Jonathan Larmour]

[-- Attachment #1: Type: text/plain, Size: 1172 bytes --]

Jonathan Larmour wrote:
> 
> Jonathan Larmour wrote:
> >
> > The eCos ARM GDB support hasn't been designed to debug user mode, only svc
> > mode so you're breaking new ground here!
> 
> Actually it's been pointed out (by Mark S) that the current version of
> vectors.S in our internal repository may handle this better. It doesn't
> support user mode debugging, but it does support debugging of the other
> privileged modes better than the current anoncvs version anyway, thanks to
> a recent overhaul. To support user mode debugging probably involves forking
> the exception handling into two paths early in the exception process. One
> way for user mode being interrupted and the other is the current handling.
> 
> I've attached it anyway.

It seems it was so new that it wasn't even in our mainline CVS at the time
I took the snapshot! And in any case I was missing some other files.

Here's a patch instead. Caveat emptor - you're on your own :).
 
Jifl
-- 
Red Hat, Rustat House, Clifton Road, Cambridge, UK. Tel: +44 (1223) 271062
--[ "You can complain because roses have thorns, or you ]--
--[  can rejoice because thorns have roses." -Lincoln   ]-- Opinions==mine

[-- Attachment #2: vectors.pat.bz2 --]
[-- Type: application/octet-stream, Size: 4690 bytes --]

[-- Attachment #3: Type: text/plain, Size: 146 bytes --]

-- 
Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
and search the list archive: http://sources.redhat.com/ml/ecos-discuss