# Re: \[PATCH 00/32\] x86/msr: Drop 32-bit MSR interfaces

- From: Jürgen Groß \<jgross@suse.com\>
- Date: 2026-06-29 08:15:23 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2026/06/17186538
- Thread: https://ratatoskr.run/linux-pm/2026/06/17185889/t.md

```text
On 29.06.26 10:06, Arnd Bergmann wrote:
> On Mon, Jun 29, 2026, at 09:01, Jürgen Groß wrote:
>> On 29.06.26 08:52, Arnd Bergmann wrote:
>>> On Mon, Jun 29, 2026, at 08:04, Juergen Gross wrote:
>>>
>>> I assume this is fine, but since you don't mention it explicitly here,
>>> please clarify what this means for 32-bit CPUs without the rdmsrq
>>> instruction. Those will continue using the same instructions as before
>>> and just change the calling conventions, right?
>>
>> Yes. I thought this would be clear from the following:
>>
>>     - They are based on primitives using 64-bit sized values anyway.
>
> Right, that was my reading of it as well, but it's not entirely
> clear when the function name is the same as the mnemonic of an
> instruction that only exists on newer CPUs and the later patch

There is no RDMSRQ instruction on any x86 CPU. Are you mixing this up with
WRMSRNS/RDMSR using an immediate for addressing the MSR?


Juergen
```

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