Re: [PATCH v2 0/3] arm64/sme: Support disabling streaming mode via ptrace on SME only systems

Thiago Jung Bauermann
2025-11-21T16:30:44Z

Luis <luis.machado.foss@gmail.com> writes:

> [off-list, as I'm having bouncing issues]
>
> Hi,
>
> On 17/11/2025 21:00, Catalin Marinas wrote:
>> From: Catalin Marinas <catalin.marinas@arm.com>
>> On Wed, 15 Oct 2025 18:56:35 +0100, Mark Brown wrote:
>>> Currently it is not possible to disable streaming mode via ptrace on SME
>>> only systems, the interface for doing this is to write via NT_ARM_SVE but
>>> such writes will be rejected on a system without SVE support. Enable this
>>> functionality by allowing userspace to write SVE_PT_REGS_FPSIMD format data
>>> via NT_ARM_SVE with the vector length set to 0 on SME only systems. Such
>>> writes currently error since we require that a vector length is specified
>>> which should minimise the risk that existing software is relying on current
>>> behaviour.
>>>
>>> [...]
>> I don't think we'll get gdb feedback soon. Thanks David for the LLDB
>> ack.
>
> Unfortunately this flew under the radar for me, and I haven´t been following these
> discussions closely.
>
> Is there someone working to rectify/validate this in GDB from Arm's side?
>
> I´d gladly review it and get it through into upstream gdb.

I will work on it next week.

--
Thiago