How does ioremap() get non-cached mappings

From: Nagendra Singh Tomar
Date: Fri Apr 16 2004 - 00:09:01 EST

ioremap() function in x86 arch code does not seem to be setting _PAGE_PCD
bit in the PTE. How then does it give non-cached mapping to MMIO mappings
for memory on some interface card. I have gone thru some old threads on
this, which have concluded that it does give non-cached mappings, and
moerover ioremap seems to work fine whenever I have used to map any PCI
card memory,
Is it guaranteed thru the means of MTRR ?


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