Le 21/04/2020 à 11:47, KONRAD Frederic a écrit :
>
>
> Le 4/20/20 à 10:43 PM, Laurent Vivier a écrit :
>> Le 20/04/2020 à 21:08, KONRAD Frederic a écrit :
>>>
>>>
>>> Le 4/20/20 à 5:46 PM, Laurent Vivier a écrit :
>>>> Le 20/04/2020 à 16:01, frederic.kon...@adacore.com a écrit :
>>>>> From: KONRAD Frederic <frederic.kon...@adacore.com>
>>>>>
>>>>> Currently "cf-core.xml" is sent to GDB when using any m68k flavor.
>>>>> Thing is
>>>>> it uses the "org.gnu.gdb.coldfire.core" feature name and gdb 8.3 then
>>>>> expects
>>>>> a coldfire FPU instead of the default m68881 FPU.
>>>>
>>>>
>>>> I checked in gdb sources and there is no cf definition.
>>>>
>>>> Moreover if I change only the cf to m68k in QEMU it seems to work in
>>>> both cases:
>>>>
>>>> diff --git a/gdb-xml/cf-core.xml b/gdb-xml/cf-core.xml
>>>> index b90af3042c..5b092d26de 100644
>>>> --- a/gdb-xml/cf-core.xml
>>>> +++ b/gdb-xml/cf-core.xml
>>>> @@ -5,7 +5,7 @@
>>>> are permitted in any medium without royalty provided the
>>>> copyright
>>>> notice and this notice are preserved. -->
>>>> <!DOCTYPE feature SYSTEM "gdb-target.dtd">
>>>> -<feature name="org.gnu.gdb.coldfire.core">
>>>> +<feature name="org.gnu.gdb.m68k.core">
>>>> <reg name="d0" bitsize="32"/>
>>>> <reg name="d1" bitsize="32"/>
>>>> <reg name="d2" bitsize="32"/>
>>>
>>> Doesn't that break gdb with coldfire?
>>>
>>>> diff --git a/gdb-xml/m68k-fp.xml b/gdb-xml/m68k-fp.xml
>>>> index 64290d1630..0ef74f7488 100644
>>>> --- a/gdb-xml/m68k-fp.xml
>>>> +++ b/gdb-xml/m68k-fp.xml
>>>> @@ -5,7 +5,7 @@
>>>> are permitted in any medium without royalty provided the
>>>> copyright
>>>> notice and this notice are preserved. -->
>>>> <!DOCTYPE feature SYSTEM "gdb-target.dtd">
>>>> -<feature name="org.gnu.gdb.coldfire.fp">
>>>> +<feature name="org.gnu.gdb.m68k.fp">
>>>> <reg name="fp0" bitsize="96" type="float" group="float"/>
>>>> <reg name="fp1" bitsize="96" type="float" group="float"/>
>>>> <reg name="fp2" bitsize="96" type="float" group="float"/>
>>>>
>>>> As I have not checked the gdb sources for that, I'd like to have your
>>>> opinion.
>>>
>>> In the GDB 8.3 sources: m68k-tdep.c:1091:
>>>
>>> feature = tdesc_find_feature (info.target_desc,
>>> "org.gnu.gdb.m68k.core");
>>> if (feature == NULL)
>>> {
>>> feature = tdesc_find_feature (info.target_desc,
>>> "org.gnu.gdb.coldfire.core");
>>> if (feature != NULL)
>>> flavour = m68k_coldfire_flavour;
>>> }
>>>
>>> Hence the change I suggested. Little later it has also:
>>>
>>> feature = tdesc_find_feature (info.target_desc,
>>> "org.gnu.gdb.coldfire.fp");
>>> if (feature != NULL)
>>> {
>>> valid_p = 1;
>>> for (i = M68K_FP0_REGNUM; i <= M68K_FPI_REGNUM; i++)
>>> valid_p &= tdesc_numbered_register (feature, tdesc_data, i,
>>> m68k_register_names[i]);
>>> if (!valid_p)
>>> {
>>> tdesc_data_cleanup (tdesc_data);
>>> return NULL;
>>> }
>>> }
>>> else
>>> has_fp = 0;
>>>
>>> Which is why I didn't made the change you suggested about the
>>> m68k-fp.xml but I
>>> just tried with this additional change and it doesn't seem to hurt.
>>
>> Thank you for your analysis, it seems a simpler patch works with
>> coldfire and m68k.
>
> Hi Laurent,
>
> Arg sorry I though I said that in an other email but apparently I forgot
> to hit
> the send button. The issue with this simpler patch is that GDB will not
> set:
>
> flavour = m68k_coldfire_flavour
>
> when we are running coldfire emulation, and that might break the ABI
> within GDB.
> According to the comments there, float are returned within D0 for
> ColdFire and
> not the other one. That's why I cared to keep them separate ie: send
> the right
> "feature name" for the right cpu we are modelling.
Yes, you are right. I've added some traces in GDB to check the result.
I trace the features pointer, the flavour, etc.
Here what I have with your patch:
coldfire:
org.gnu.gdb.m68k.core (nil)
org.gnu.gdb.coldfire.core 0x10e6bf0
org.gnu.gdb.coldfire.fp 0x1197a70
tdep->fpregs_present 1
dep->flavour m68k_coldfire_flavour
floatformats_ieee_double
set_gdbarch_decr_pc_after_break 2
tdep->float_return 0
m68k:
org.gnu.gdb.m68k.core 0x1c21310
org.gnu.gdb.coldfire.fp 0x1b65d10
tdep->fpregs_present 1
tdep->flavour m68k_no_flavour
floatformats_m68881_ext
tdep->float_return 1
All the values are ok, but I try change "org.gnu.gdb.coldfire.fp" to
"org.gnu.gdb.m68k.fp" in gdb-xml/m68k-fp.xml and I think it breaks
something because tdep->fpregs_present turns to be 0:
m68k:
org.gnu.gdb.m68k.core 0x2796b60
org.gnu.gdb.coldfire.fp (nil)
tdep->fpregs_present 0
tdep->flavour m68k_no_flavour
floatformats_m68881_ext
I also tried my patch and as you said it doesn't set the good
floatformat for coldfire (and not the good value for fpregs_present for
m68k):
coldfire:
org.gnu.gdb.m68k.core 0xbdb320
org.gnu.gdb.coldfire.fp 0xbd38d0
tdep->fpregs_present 1
tdep->flavour m68k_no_flavour
floatformats_m68881_ext
tdep->float_return 1
m68k:
org.gnu.gdb.m68k.core 0x1e2cb60
org.gnu.gdb.coldfire.fp (nil)
tdep->fpregs_present 0
tdep->flavour m68k_no_flavour
floatformats_m68881_ext
Thanks,
Laurent
