Messages in this thread | | | Date | Mon, 17 Oct 2022 22:52:27 +0200 | From | "Arnd Bergmann" <> | Subject | Re: [RFC PATCH 7/8] mm/ioremap: Consider IOREMAP space in generic ioremap |
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On Mon, Oct 17, 2022, at 2:50 PM, Michael Ellerman wrote: > "Arnd Bergmann" <arnd@arndb.de> writes: >> >> My guess is that there was no technical reason for this, other >> than having no reason to change the behavior at the time. > > I think the immediate reason for it is that on some CPUs we have to use > 4K pages in the HPT for IO mappings, but PAGE_SIZE == 64K, and we can > only have a single page size per segment (256M or 1T).
Right, makes sense. Both the original patch, or the variant with defining IOREMAP_START everywhere seem fine to me then.
Arnd
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