Re: [PATCH v1] target/m68k: fix gdb for m68xxx

["Alex Bennée" <alex.bennee@linaro.org>]

frederic.konrad@adacore.com writes:

> From: KONRAD Frederic <frederic.konrad@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.
>
> This is not OK because the m68881 floats registers are 96 bits wide so it
> crashes GDB with the following error message:
>
> (gdb) target remote localhost:7960
> Remote debugging using localhost:7960
> warning: Register "fp0" has an unsupported size (96 bits)
> warning: Register "fp1" has an unsupported size (96 bits)
> ...
> Remote 'g' packet reply is too long (expected 148 bytes, got 180 bytes):    \
>   00000000000[...]0000
>
> With this patch: qemu-system-m68k -M none -cpu m68020 -s -S
>
> (gdb) tar rem :1234
> Remote debugging using :1234
> warning: No executable has been specified and target does not support
> determining executable automatically.  Try using the "file" command.
> 0x00000000 in ?? ()
> (gdb) p $fp0
> $1 = nan(0xffffffffffffffff)
>
> Signed-off-by: KONRAD Frederic <frederic.konrad@adacore.com>

Well it solves the connection issue - but the FP values are still
hopelessly broken, from float_convs:

  from single: f32(-0x1.1874b200000000000000p+103:0xf30c3a59)

in gdb

  fp0            <invalid float value> (raw 0x8c3a5900000000004066)

> ---
>  configure             |  2 +-
>  gdb-xml/m68k-core.xml | 29 +++++++++++++++++++++++++++++
>  target/m68k/cpu.c     | 30 +++++++++++++++++++++++++-----
>  3 files changed, 55 insertions(+), 6 deletions(-)
>  create mode 100644 gdb-xml/m68k-core.xml
>
> diff --git a/configure b/configure
> index 23b5e93..2b07b85 100755
> --- a/configure
> +++ b/configure
> @@ -7825,7 +7825,7 @@ case "$target_name" in
>    ;;
>    m68k)
>      bflt="yes"
> -    gdb_xml_files="cf-core.xml cf-fp.xml m68k-fp.xml"
> +    gdb_xml_files="cf-core.xml cf-fp.xml m68k-core.xml m68k-fp.xml"
>      TARGET_SYSTBL_ABI=common
>    ;;
>    microblaze|microblazeel)
> diff --git a/gdb-xml/m68k-core.xml b/gdb-xml/m68k-core.xml
> new file mode 100644
> index 0000000..5b092d2
> --- /dev/null
> +++ b/gdb-xml/m68k-core.xml
> @@ -0,0 +1,29 @@
> +<?xml version="1.0"?>
> +<!-- Copyright (C) 2008 Free Software Foundation, Inc.
> +
> +     Copying and distribution of this file, with or without modification,
> +     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.m68k.core">
> +  <reg name="d0" bitsize="32"/>
> +  <reg name="d1" bitsize="32"/>
> +  <reg name="d2" bitsize="32"/>
> +  <reg name="d3" bitsize="32"/>
> +  <reg name="d4" bitsize="32"/>
> +  <reg name="d5" bitsize="32"/>
> +  <reg name="d6" bitsize="32"/>
> +  <reg name="d7" bitsize="32"/>
> +  <reg name="a0" bitsize="32" type="data_ptr"/>
> +  <reg name="a1" bitsize="32" type="data_ptr"/>
> +  <reg name="a2" bitsize="32" type="data_ptr"/>
> +  <reg name="a3" bitsize="32" type="data_ptr"/>
> +  <reg name="a4" bitsize="32" type="data_ptr"/>
> +  <reg name="a5" bitsize="32" type="data_ptr"/>
> +  <reg name="fp" bitsize="32" type="data_ptr"/>
> +  <reg name="sp" bitsize="32" type="data_ptr"/>
> +
> +  <reg name="ps" bitsize="32"/>
> +  <reg name="pc" bitsize="32" type="code_ptr"/>
> +
> +</feature>
> diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c
> index 9445fcd..976e624 100644
> --- a/target/m68k/cpu.c
> +++ b/target/m68k/cpu.c
> @@ -297,6 +297,21 @@ static void m68k_cpu_class_init(ObjectClass *c, void *data)
>      dc->vmsd = &vmstate_m68k_cpu;
>  }
>  
> +static void m68k_cpu_class_init_m68k_core(ObjectClass *c, void *data)
> +{
> +    CPUClass *cc = CPU_CLASS(c);
> +
> +    cc->gdb_core_xml_file = "m68k-core.xml";
> +}
> +
> +#define DEFINE_M68K_CPU_TYPE_WITH_CLASS(cpu_model, initfn, classinit)      \
> +    {                                                                      \
> +        .name = M68K_CPU_TYPE_NAME(cpu_model),                             \
> +        .instance_init = initfn,                                           \
> +        .parent = TYPE_M68K_CPU,                                           \
> +        .class_init = classinit,                                           \
> +    }
> +
>  #define DEFINE_M68K_CPU_TYPE(cpu_model, initfn) \
>      {                                           \
>          .name = M68K_CPU_TYPE_NAME(cpu_model),  \
> @@ -314,11 +329,16 @@ static const TypeInfo m68k_cpus_type_infos[] = {
>          .class_size = sizeof(M68kCPUClass),
>          .class_init = m68k_cpu_class_init,
>      },
> -    DEFINE_M68K_CPU_TYPE("m68000", m68000_cpu_initfn),
> -    DEFINE_M68K_CPU_TYPE("m68020", m68020_cpu_initfn),
> -    DEFINE_M68K_CPU_TYPE("m68030", m68030_cpu_initfn),
> -    DEFINE_M68K_CPU_TYPE("m68040", m68040_cpu_initfn),
> -    DEFINE_M68K_CPU_TYPE("m68060", m68060_cpu_initfn),
> +    DEFINE_M68K_CPU_TYPE_WITH_CLASS("m68000", m68000_cpu_initfn,
> +                                    m68k_cpu_class_init_m68k_core),
> +    DEFINE_M68K_CPU_TYPE_WITH_CLASS("m68020", m68020_cpu_initfn,
> +                                    m68k_cpu_class_init_m68k_core),
> +    DEFINE_M68K_CPU_TYPE_WITH_CLASS("m68030", m68030_cpu_initfn,
> +                                    m68k_cpu_class_init_m68k_core),
> +    DEFINE_M68K_CPU_TYPE_WITH_CLASS("m68040", m68040_cpu_initfn,
> +                                    m68k_cpu_class_init_m68k_core),
> +    DEFINE_M68K_CPU_TYPE_WITH_CLASS("m68060", m68060_cpu_initfn,
> +                                    m68k_cpu_class_init_m68k_core),
>      DEFINE_M68K_CPU_TYPE("m5206", m5206_cpu_initfn),
>      DEFINE_M68K_CPU_TYPE("m5208", m5208_cpu_initfn),
>      DEFINE_M68K_CPU_TYPE("cfv4e", cfv4e_cpu_initfn),


-- 
Alex Bennée