> On Feb 2, 2024, at 11:26 PM, Stephen Hemminger <step...@networkplumber.org>
> wrote:
>
> Caution: This message originated from an External Source. Use proper caution
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>
>
> On Fri, 2 Feb 2024 11:32:29 -0800
> Andrew Boyer <andrew.bo...@amd.com> wrote:
>
>> From: Neel Patel <neel.pa...@amd.com>
>>
>> This memory may be changed by the hardware, so the volatile
>> keyword is required for correctness.
>>
>> Fixes: e86a6fcc7cf3 ("net/ionic: add optimized non-scattered Rx/Tx")
>> cc: sta...@dpdk.org
>>
>> Signed-off-by: Andrew Boyer <andrew.bo...@amd.com>
>> Signed-off-by: Neel Patel <neel.pa...@amd.com>
>
> In general barriers are better than volatile.
> Volatile is a compiler not hardware construct really.
>
> https://www.kernel.org/doc/html/latest/process/volatile-considered-harmful.html
Thanks for looking. The goal here is to prevent inappropriate compiler
optimization.
>From the link you posted:
> Pointers to data structures in coherent memory which might be modified by I/O
> devices can, sometimes, legitimately be volatile. A ring buffer used by a
> network adapter, where that adapter changes pointers to indicate which
> descriptors have been processed, is an example of this type of situation.
Doesn't that sound like what we are doing?
Thanks,
Andrew
