Re: [PATCH 2/2] make ioremap_wc() x86 only (for the time being)

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

On 3/30/26 4:22 PM, Oleksii Kurochko wrote:
> On 2/19/26 4:53 PM, Jan Beulich wrote:
> > Its use in domain building is questionable: Already at the point both 
> > uses
> > were introduced, ioremap_cache() existed. I can't see why kernel and
> > initrd would need mapping WC, when at the same time other similar 
> > mappings
> > (in common/device-tree/) are done WB.
> >
> > With those uses replaced, neither Arm nor RISC-V have a need for the
> > function anymore.
> It is okay for RISC-V, but for Arm, IIRC, likely it was done because 
> guest might start with cache disabled and PAGE_HYPERVISOR_WC on Arm uses 
> "Normal Non-cacheable" what could lead to that guest won't see some part 
> of kernel and/or initrd as it could be in a cache and won't be flushed 
> to RAM.
> But probably I misremembered something and 
> clean_and_invalidate_dcache_va_range() or something similar should be 
> called before guest is laucned.
okay, so for this case copy_to_guest_phys_flush_dcache() is called after 
initrd and kernel are loaded.
Then it looks okay to me for Arm too.

~ Oleksii