patch regarding 'RTEMS not booting with Qemu PREP larger than 256Mb'

Gedare Bloom gedare at rtems.org
Tue Mar 6 17:36:02 UTC 2018


Éric

It would be preferable if you could create the ticket, so we have the
right "reporter" in mind later.

Gedare

On Tue, Mar 6, 2018 at 12:25 PM, Éric Tremblay
<e.tremblay at axis-canada.com> wrote:
> Hi Gedare, Joel,
> Unfortunately I do not have access to hw so I cannot test in this
> environment.
>
> Do you want me to create the ticket or one of you will take care of it?
>
> Thanks,
> Eric
>
> On Tue, Mar 6, 2018 at 12:02 PM, Gedare Bloom <gedare at rtems.org> wrote:
>>
>> On Mon, Mar 5, 2018 at 5:37 PM, Joel Sherrill <joel at rtems.org> wrote:
>> > Can you file a ticket with the patch attached? We don't change things on
>> > a
>> > release
>> > branch without a ticket? devel.rtems.org
>> >
>> +1
>>
>> > Are you able to test this on real hardware? It touches files in shared
>> > which
>> > will
>> > be used by multiple powerpc BSPs so it would be good to have feedback on
>> > real HW.
>> >
>> +2
>>
>> This should be verified on hw before applying especially to a release.
>>
>> If it affects hw, also change the comments to just say "greater than
>> 256 MiB" without specifying qemu -m option.
>>
>> > FWIW we are trying to wrap up a set of patches for a 4.11 release and it
>> > would
>> > be good to have this in the ticket queue for consideration.
>> >
>> > Thanks.
>> >
>> > --joel
>> >
>> >
>> > On Mon, Mar 5, 2018 at 2:31 PM, Éric Tremblay
>> > <e.tremblay at axis-canada.com>
>> > wrote:
>> >>
>> >> Hi,
>> >> I posted a question last week about a strange behavior I was getting
>> >> using
>> >> RTEMS with qemu-system-ppc.  Anytime I was specifying more than 256Mb
>> >> of
>> >> memory using the -m option the RTEMS kernel was not booting.  Here is
>> >> an
>> >> example of command line I was using:
>> >>
>> >> qemu-system-ppc  -M prep -kernel ./hello.ralf  -bios
>> >> /home/qemu_fakerom/qemu_fakerom.bin -cpu 750cxe -nographic -no-reboot
>> >> -m 384
>> >>
>> >> Model:
>> >> Serial:
>> >> Processor/Bus frequencies (Hz): 300000000/100000000
>> >> Time Base Divisor: 1000
>> >> Memory Size: 18000000
>> >> Residual: 102afd4 (length 27148)
>> >>
>> >> PCI: Probing PCI hardware
>> >>
>> >> RTEMS 4.x/PPC load:
>> >> Uncompressing the kernel...
>> >> Kernel at 0x00000000, size=0x495b0
>> >> Initrd at 0x00000000, size=0x0
>> >> Residual data at 0x0004a000
>> >> Command line at 0x00051000
>> >> done
>> >> Now booting...                                 <<<<<<<<<<<<<<<<
>> >> execution
>> >> stuck here
>> >>
>> >>
>> >> I have spent quite some time debugging this issue and I traced it back
>> >> to
>> >> two issues for which I am submitting a patch.  Please understand this
>> >> is my
>> >> first time using RTEMS and debugging a bootloader so my patch might not
>> >> be
>> >> accurate but it does fix the behavior I mentioned above.  With this
>> >> patch I
>> >> can successfully launch a "Hello World" and specify more memory (-m 512
>> >> for
>> >> example).
>> >>
>> >> My patch is quite simple since it simply allows the system to access
>> >> section of memory.  Please let me know if this is a suitable
>> >> correction, if
>> >> this is totally wrong I would like to know how this could be fixed
>> >> since our
>> >> application will use around 512Mb of memory and the current state of
>> >> things
>> >> won't work.
>> >>
>> >> Thank you for your cooperation,
>> >> Eric
>> >>
>> >> PS: I am using RTEMS release 4.11.3.
>> >>        I am using Qemu v 2.5.0
>> >>        I am running in a Linux Ubuntu VM (intel 64 bits)
>> >>
>> >>
>> >>
>> >>
>> >>  c/src/lib/libbsp/powerpc/shared/start/start.S      | 18
>> >> ++++++++++++++++++
>> >>  c/src/lib/libbsp/powerpc/shared/startup/bspstart.c | 18
>> >> ++++++++++++++++++
>> >>  2 files changed, 36 insertions(+)
>> >>
>> >> diff --git a/c/src/lib/libbsp/powerpc/shared/start/start.S
>> >> b/c/src/lib/libbsp/powerpc/shared/start/start.S
>> >> index 729c89c40b..532c1f9ee4 100644
>> >> --- a/c/src/lib/libbsp/powerpc/shared/start/start.S
>> >> +++ b/c/src/lib/libbsp/powerpc/shared/start/start.S
>> >> @@ -93,6 +93,24 @@ __rtems_entry_point:
>> >>   mtspr IBAT0L,r8
>> >>   mtspr IBAT0U,r11
>> >>   isync
>> >> +/*   Map section where residual is located if outside
>> >> + *   the first 256Mb of RAM.  This is to support cases
>> >> + *   where the user supplies the -m option with Qemu
>> >> + *   in order to have more memory available to the system.
>> >> + */
>> >> + mr r9, r1    /* Get where residual was mapped */
>> >> + lis r12,0xf0000000 at h
>> >> + and r9,r9,r12
>> >> + cmpi 0,1,r9, 0
>> >> + beq skip_BAT1_config
>> >> + isync
>> >> + ori r11,r9,0x1ffe
>> >> + mtspr DBAT1L,r8 /* N.B. 6xx (not 601) have valid */
>> >> + mtspr DBAT1U,r11 /* bit in upper BAT register */
>> >> + mtspr IBAT1L,r8
>> >> + mtspr IBAT1U,r11
>> >> + isync
>> >> +skip_BAT1_config:
>> >>
>> >>  /*
>> >>   * we now have the 1st 256M of ram mapped with the bats. We are still
>> >> diff --git a/c/src/lib/libbsp/powerpc/shared/startup/bspstart.c
>> >> b/c/src/lib/libbsp/powerpc/shared/startup/bspstart.c
>> >> index 5a97cc8531..f80835b117 100644
>> >> --- a/c/src/lib/libbsp/powerpc/shared/startup/bspstart.c
>> >> +++ b/c/src/lib/libbsp/powerpc/shared/startup/bspstart.c
>> >> @@ -300,6 +300,24 @@ void bsp_start( void )
>> >>     */
>> >>    _BSP_clear_hostbridge_errors(0 /* enableMCP */, 0/*quiet*/);
>> >>
>> >> +   if (BSP_mem_size > 0x10000000)
>> >> +   {
>> >> +   /* Support cases with qemu supplied -m option and mem size larger
>> >> than
>> >> 256Mb.
>> >> +    *
>> >> +    * We use BAT3 in order to obtain access to the top section of the
>> >> RAM.
>> >> +    * We also need to do this just before setting up the page table
>> >> because
>> >> +    * this is where the page table will be located.
>> >> +    */
>> >> +   const unsigned int mem256Count = (BSP_mem_size / 0x10000000);
>> >> +   const unsigned int BAT3Addr    = ((BSP_mem_size % 0x10000000)    ?
>> >> + (mem256Count     * 0x10000000) :
>> >> + ((mem256Count-1) * 0x10000000));
>> >> +      setdbat(3, BAT3Addr, BAT3Addr, 0x10000000, IO_PAGE);
>> >> +#ifdef SHOW_MORE_INIT_SETTINGS
>> >> +      printk("Setting up BAT3 for large memory support. (BAT3 -->
>> >> 0x%x)\n", BAT3Addr);
>> >> +#endif
>> >> +   }
>> >> +
>> >>    /* Allocate and set up the page table mappings
>> >>     * This is only available on >604 CPUs.
>> >>     *
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> _______________________________________________
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>> >> devel at rtems.org
>> >> http://lists.rtems.org/mailman/listinfo/devel
>> >
>> >
>> >
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