Re: [PATCH v5 6/8] string: introduce memcpy_nt() helpers

On Mon, Jul 6, 2026 at 11:18:48AM +0200, [email protected] wrote:

> > +
> > +#define __HAVE_ARCH_MEMCPY_NT 1
> > +/*
> > + * Reuse the existing x86 flushcache backend as the nt copy primitive.
> > + * Callers pair it with memcpy_nt_drain() when later stores must be
> > + * ordered after the copy.
> > + */
> > +static __always_inline void memcpy_nt(void *dst, const void *src, size_t cnt)
> > +{
> > +	memcpy_flushcache(dst, src, cnt);
> > +}
> 
> In particular if you end up with a single function (that jsut requires a write
> memory barrier afterwards), please make this
> 
> #define memcpy_nt memcpy_nt
> 
> instead.

Thanks for the review.

Just to make sure I understood this correctly: do you mean that, rather
than using a separate __HAVE_ARCH_MEMCPY_NT feature macro, you would
prefer the usual self-macro override pattern, with

    #define memcpy_nt memcpy_nt

in arch/x86/include/asm/string_64.h and the generic fallback kept under
#ifndef memcpy_nt in include/linux/string.h?

If so, I can rework it that way in v6. I would likely use the same
pattern for memcpy_nt_drain() as well, unless you would prefer
otherwise.

Thanks,
Zhe