Re: Question Regarding Int Cast Error in GDB Python

[Vacha Bhavsar via Gdb <gdb@sourceware.org>]

Hi,

Apologies, it seems I pasted the wrong snippet in the original email.
The code in my reply just prior to this is the correct code. The snippet
that
should have been included in the first email, which causes the error, is
the one below:

v = gdb.parse_and_eval(reg)
report(str(v.type) == "uint128_t", "size of %s" % (reg))
report(int(v) == MAGIC, "%s is 0x%x" % (reg, MAGIC))

Sorry for the confusion!


On Mon, Aug 25, 2025 at 9:23 AM Vacha Bhavsar <
vacha.bhavsar@oss.qualcomm.com> wrote:

> Hi,
>
> We are testing the ZA by tiles and tile slices. I've included a larger
> snippet
> of the code below:
>
> for i in range(0, 4):
>         for j in range(0, 4):
>             for k in range(0, 4):
>                 cmd = "set $za%dhq%d[%d] = 0x%x" % (i, j, k, MAGIC)
>                 gdb.execute(cmd)
>                 report(True, "%s" % cmd)
>         for j in range(0, 4):
>             for k in range(0, 4):
>                 reg = "$za%dhq%d[%d]" % (i, j, k)
>                 v = gdb.parse_and_eval(reg)
>                 report(str(v.type) == "uint128_t",
>                     "size of %s" % (reg))
>                 report(int(v) == MAGIC, "%s is 0x%x" % (reg, MAGIC))
>
> So in this case we see the error when we try to test za0hq0[0] when
> v is cast to an int.
>
> On Mon, Aug 25, 2025 at 4:35 AM Luis <luis.machado.foss@gmail.com> wrote:
>
>> On 8/22/25 19:21, Vacha Bhavsar via Gdb wrote:
>> > Hi,
>> >
>> > I am developing a patch for QEMU which would allow QEMU to expose
>> > SME registers, such as the ZA storage, via gdbstub to a remote
>> > gdb client session. I am working to write a simple test case for
>> > this change which simply sets the value of the za register, then
>> > reads it and ensures what is read is equivalent to what was set.
>> >
>> > The full test case can be found here:
>> >
>> > https://lists.gnu.org/archive/html/qemu-devel/2025-08/msg01815.html
>> >
>> > However, it seems there is an issue in the int cast in the following
>> > code:
>> >
>> > v = gdb.parse_and_eval(reg)
>> > report(str(v.type) == "uint8_t", "size of %s" % (reg))
>> > report(int(v) == 0x1, "%s is 0x%x" % (reg, 0x1))
>>
>> If reg is ZA, I´d expect gdb to have difficulties casting the whole
>> array to an int, hence the message about not managing to operate on
>> integers larger than 8 bytes.
>>
>> How are you testing ZA? Byte by byte?
>>
>> >
>> > This results in the following error:
>> >
>> > Python Exception <class 'gdb.error'>: That operation is not available
>> > on integers of more than 8 bytes.
>> > Error occurred in Python: That operation is not available on integers
>> > of more than 8 bytes.
>> >
>> > After running various tests with different host architectures, gdb
>> > versions, python version and int casting included and excluded, we
>> > are seeing that this issue only seems to arise when the int cast is
>> > included and the gdb used is GNU gdb (Ubuntu 15.0.50.20240403-0ubuntu1)
>> > 15.0.50.20240403-git (regardless of python version and host
>> architecture).
>> >
>> > The test results are presented below. I was hoping to get some guidance
>> > regarding this error and what may be the cause if it indeed stems from
>> > this specific version of gdb?
>> >
>> > Thanks,
>> > Vacha
>> >
>> >
>> >   gdb     gdb target           python   host          int cast    status
>> > version support              version  architecture
>> > 16.3 --enable-targets=all 3.11.13   x86        yes        pass
>> > 16.3 --enable-targets=all 3.11.13   x86         no        pass
>> > 16.3 --enable-targets=all 3.10.18   x86        yes        pass
>> > 16.3 --enable-targets=all 3.10.18   x86         no        pass
>> > 16.3 --enable-targets=all 3.8.10    x86        yes        pass
>> > 16.3 --enable-targets=all 3.8.10    x86          no        pass
>> >
>> > 16.3   aarch64             3.11.0rc1 aarch64      yes        pass
>> > 16.3   aarch64             3.11.0rc1 aarch64       no        pass
>> > 16.3   aarch64             3.10.12   aarch64      yes        pass
>> > 16.3   aarch64             3.10.12   aarch64       no        pass
>> >
>> > 15.0   multiarch           3.10.12   aarch64      yes        fail
>> > 15.0   multiarch           3.10.12   aarch64      no        pass
>> > 15.0   multiarch          3.11.0rc1 aarch64      yes        fail
>> > 15.0   multiarch          3.11.0rc1 aarch64      no        pass
>> >
>> > 15.0   multiarch          3.8.10      x86            yes        fail
>> > 15.0   multiarch          3.8.10      x86             no        pass
>> > 15.0   multiarch        3.11.13      x86            yes        fail
>> > 15.0   multiarch        3.11.13      x86             no        pass
>> > 15.0   multiarch        3.10.18      x86            yes        fail
>> > 15.0   multiarch        3.10.18     x86             no        pass
>>
>>