[ABANDONED] Reading all ARM NEON registers with j-link gdbserver on Cortex A9

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  • [ABANDONED] Reading all ARM NEON registers with j-link gdbserver on Cortex A9

    The GDB server does not reflect all NEON registers, at least not on Cortex A9.

    There are 32 double word registers d0-d31 which can also be seen as 16 quad word registers q0-15.

    Additionally, there are multiple possible formats like floating point and fixed point.

    Please add this functionality as you cannot see the complete state of any armv7-a using jlink gdb server which is really important.

    See a correctly implemented target description in the qemu project
    github.com/qemu/qemu/blob/master/gdb-xml/arm-neon.xml

    When I set the tdisc manually, I get error messages "packet reply is too long".

    <?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.arm.vfp">
    <vector id="neon_uint8x8" type="uint8" count="8"/>
    <vector id="neon_uint16x4" type="uint16" count="4"/>
    <vector id="neon_uint32x2" type="uint32" count="2"/>
    <vector id="neon_float32x2" type="ieee_single" count="2"/>
    <union id="neon_d">
    <field name="u8" type="neon_uint8x8"/>
    <field name="u16" type="neon_uint16x4"/>
    <field name="u32" type="neon_uint32x2"/>
    <field name="u64" type="uint64"/>
    <field name="f32" type="neon_float32x2"/>
    <field name="f64" type="ieee_double"/>
    </union>
    <vector id="neon_uint8x16" type="uint8" count="16"/>
    <vector id="neon_uint16x8" type="uint16" count="8"/>
    <vector id="neon_uint32x4" type="uint32" count="4"/>
    <vector id="neon_uint64x2" type="uint64" count="2"/>
    <vector id="neon_float32x4" type="ieee_single" count="4"/>
    <vector id="neon_float64x2" type="ieee_double" count="2"/>
    <union id="neon_q">
    <field name="u8" type="neon_uint8x16"/>
    <field name="u16" type="neon_uint16x8"/>
    <field name="u32" type="neon_uint32x4"/>
    <field name="u64" type="neon_uint64x2"/>
    <field name="f32" type="neon_float32x4"/>
    <field name="f64" type="neon_float64x2"/>
    </union>
    <reg name="d0" bitsize="64" type="neon_d"/>
    <reg name="d1" bitsize="64" type="neon_d"/>
    <reg name="d2" bitsize="64" type="neon_d"/>
    <reg name="d3" bitsize="64" type="neon_d"/>
    <reg name="d4" bitsize="64" type="neon_d"/>
    <reg name="d5" bitsize="64" type="neon_d"/>
    <reg name="d6" bitsize="64" type="neon_d"/>
    <reg name="d7" bitsize="64" type="neon_d"/>
    <reg name="d8" bitsize="64" type="neon_d"/>
    <reg name="d9" bitsize="64" type="neon_d"/>
    <reg name="d10" bitsize="64" type="neon_d"/>
    <reg name="d11" bitsize="64" type="neon_d"/>
    <reg name="d12" bitsize="64" type="neon_d"/>
    <reg name="d13" bitsize="64" type="neon_d"/>
    <reg name="d14" bitsize="64" type="neon_d"/>
    <reg name="d15" bitsize="64" type="neon_d"/>
    <reg name="d16" bitsize="64" type="neon_d"/>
    <reg name="d17" bitsize="64" type="neon_d"/>
    <reg name="d18" bitsize="64" type="neon_d"/>
    <reg name="d19" bitsize="64" type="neon_d"/>
    <reg name="d20" bitsize="64" type="neon_d"/>
    <reg name="d21" bitsize="64" type="neon_d"/>
    <reg name="d22" bitsize="64" type="neon_d"/>
    <reg name="d23" bitsize="64" type="neon_d"/>
    <reg name="d24" bitsize="64" type="neon_d"/>
    <reg name="d25" bitsize="64" type="neon_d"/>
    <reg name="d26" bitsize="64" type="neon_d"/>
    <reg name="d27" bitsize="64" type="neon_d"/>
    <reg name="d28" bitsize="64" type="neon_d"/>
    <reg name="d29" bitsize="64" type="neon_d"/>
    <reg name="d30" bitsize="64" type="neon_d"/>
    <reg name="d31" bitsize="64" type="neon_d"/>

    <reg name="q0" bitsize="128" type="neon_q"/>
    <reg name="q1" bitsize="128" type="neon_q"/>
    <reg name="q2" bitsize="128" type="neon_q"/>
    <reg name="q3" bitsize="128" type="neon_q"/>
    <reg name="q4" bitsize="128" type="neon_q"/>
    <reg name="q5" bitsize="128" type="neon_q"/>
    <reg name="q6" bitsize="128" type="neon_q"/>
    <reg name="q7" bitsize="128" type="neon_q"/>
    <reg name="q8" bitsize="128" type="neon_q"/>
    <reg name="q9" bitsize="128" type="neon_q"/>
    <reg name="q10" bitsize="128" type="neon_q"/>
    <reg name="q10" bitsize="128" type="neon_q"/>
    <reg name="q12" bitsize="128" type="neon_q"/>
    <reg name="q13" bitsize="128" type="neon_q"/>
    <reg name="q14" bitsize="128" type="neon_q"/>
    <reg name="q15" bitsize="128" type="neon_q"/>

    <reg name="fpsid" bitsize="32" type="int" group="float"/>
    <reg name="fpscr" bitsize="32" type="int" group="float"/>
    <reg name="fpexc" bitsize="32" type="int" group="float"/>
    </feature>

    Thanks!

  • Hello,

    Thank you for your inquiry.
    We will discuss your request internally and see if GDBServer can be improved in that regard.

    Best regards,
    Nino
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