Re: Linux 2.4.17 bug, mmap of /dev/mem

Re: Linux 2.4.17 bug, mmap of /dev/mem

[David Ashley]

I've traced the problem down to arch/ppc/mm/hashtable.S. When
there is a page fault, the function hash_page gets called. This does
some hashing and writes the hash values into a table located at
0xc0180000. That is the default value, before patching. These writes are
what is corrupting the linux kernel, because they are on top of linux
itself.

In arch/ppc/mm/ppc_mmu.c the function MMU_init_hw is called, but
since the 8260 doesn't have the CPU_FTR_HPTE_TABLE feature, the
hash table is never allocated and the hash_page_patch_* never get updated.

Turning on the CPU_FTR_HPTE_TABLE for the 8260 doesn't fix the problem.

I'm out of my depth here. This is a bug in linux, I know that much. But I
don't know what is supposed to happen during a page fault. So I need help
in resolving this.

Thanks--
Dave

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Re: Linux 2.4.17 bug, mmap of /dev/mem

[Dan Malek]

David Ashley wrote:

> I've traced the problem down to arch/ppc/mm/hashtable.S. When
> there is a page fault, the function hash_page gets called.

In the case of a 603 core, hash_page is called for DSI (Data Access)
faults.  However, if the feature indicates there is no HPTE, the
hash_page function is patched to simply return.  You can't look at
the code in hashtable.S and know how it is going to work for a particular
implementation because it is patched at initialization to change
it's behavior.

> .....This does
> some hashing and writes the hash values into a table located at
> 0xc0180000.

When your kernel boots, does it print a message to indicate it has allocated
a hash table?

> In arch/ppc/mm/ppc_mmu.c the function MMU_init_hw is called, but
> since the 8260 doesn't have the CPU_FTR_HPTE_TABLE feature, the
> hash table is never allocated and the hash_page_patch_* never get updated.


Oh, I just looked at a variety of different versions back to 2.4.11, and it
is patched just as I described above.


	-- Dan


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gdbserver ppc8xx

[Owen Green]

Hi all,

could anyone tell me where can I find a gdbserver that
works with mpc8xx processor? Where can I find sources
that compiles for 8xx?

I have already tried with mvista HHL2.0 Journeyman
edition but I got something like:
#gdbserver :7777 /bin/test
Process /bin/test created; pid = 48
getprotobyname:Sucess.
Exiting
#
What could be wrong? Any tip will be very appreciate.

Thanks in advance,

   Owen.


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Re: gdbserver ppc8xx

[Wolfgang Denk]

In message <20020227214749.38142.qmail@web20110.mail.yahoo.com> you wrote:
>
> could anyone tell me where can I find a gdbserver that
> works with mpc8xx processor? Where can I find sources

Well, use the one that came with HHL-2.0?

> that compiles for 8xx?

gdb-5.1 sources?

> I have already tried with mvista HHL2.0 Journeyman
> edition but I got something like:
> #gdbserver :7777 /bin/test
> Process /bin/test created; pid = 48
> getprotobyname:Sucess.
> Exiting
> #
> What could be wrong? Any tip will be very appreciate.

What do you think getprotobyname() does? [Hint: man getprotobyname  -
pay  special  attention  to  the  FILES section]. Hint2: There may be
other  networ  related  files  missing  on  your  system,  too,  like
/etc/services, or /lib/libnss_*

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
Veni, Vidi, VISA:
        I came, I saw, I did a little shopping.

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Re: gdbserver ppc8xx

[Christian Pellegrin]

On Wed, 27 Feb 2002, Owen Green wrote:

>
> Hi all,
>
> could anyone tell me where can I find a gdbserver that
> works with mpc8xx processor? Where can I find sources
> that compiles for 8xx?
>
> I have already tried with mvista HHL2.0 Journeyman
> edition but I got something like:
> #gdbserver :7777 /bin/test
> Process /bin/test created; pid = 48
> getprotobyname:Sucess.
> Exiting
> #
> What could be wrong? Any tip will be very appreciate.
>

just copy /etc/protocols from whatever distro you like. Bye!


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Re: gdbserver ppc8xx

[Owen Green]

--- Christian Pellegrin <chri@infis.univ.trieste.it>
wrote:
> On Wed, 27 Feb 2002, Owen Green wrote:
>
> > edition but I got something like:
> > #gdbserver :7777 /bin/test
> > Process /bin/test created; pid = 48
> > getprotobyname:Sucess.
> > Exiting
> > #
> just copy /etc/protocols from whatever distro you
> like. Bye!
>

This did not work, I got the getprotobyname: Sucess,
what means my /etc/protocols have the entry for tcp.
Thanks anyway.


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RE: gdbserver ppc8xx

[Goddeeris Frederic]

Did you try using strace? This can give you info about why gdbserver quits.

I also had a problem with gdbserver and this is the way I solved it...

Fred

-----Original Message-----
From: Owen Green
To: Christian Pellegrin
Cc: linuxppc-embedded@lists.linuxppc.org
Sent: 2/28/02 2:50 PM
Subject: Re: gdbserver ppc8xx


--- Christian Pellegrin <chri@infis.univ.trieste.it>
wrote:
> On Wed, 27 Feb 2002, Owen Green wrote:
>
> > edition but I got something like:
> > #gdbserver :7777 /bin/test
> > Process /bin/test created; pid = 48
> > getprotobyname:Sucess.
> > Exiting
> > #
> just copy /etc/protocols from whatever distro you
> like. Bye!
>

This did not work, I got the getprotobyname: Sucess,
what means my /etc/protocols have the entry for tcp.
Thanks anyway.


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RE: gdbserver ppc8xx

[Christian Pellegrin]

>
> This did not work, I got the getprotobyname: Sucess,
> what means my /etc/protocols have the entry for tcp.
> Thanks anyway.
>

if you are ultra-lazy and like bad code just edit remote-utils.c and
hardocde protocol number for TCP .... shouldn't chage shortly I guess ;-).

NSS is a hassle with embedded systems since is far too general .... even
busybox bypasses it ;-)

Bye!


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RE: gdbserver ppc8xx

[Owen Green]

Thank you all guys for the tips,
gdbserver was not working because linbss_files.so.2
was not present on my  system /lib.
By the way, why this was not shown when I typed:
readelf gdbserver -d ?

Thanks in advance,

Owen.


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Re: gdbserver ppc8xx

[Mark Hatle]

Owen Green wrote:
>
> Thank you all guys for the tips,
> gdbserver was not working because linbss_files.so.2
> was not present on my  system /lib.
> By the way, why this was not shown when I typed:
> readelf gdbserver -d ?
>
> Thanks in advance,

libnss* is dlopened by glibc.

--Mark

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