Lines Matching refs:PAT
2 PAT (Page Attribute Table)
4 x86 Page Attribute Table (PAT) allows for setting the memory attribute at the
5 page level granularity. PAT is complementary to the MTRR settings which allows
6 for setting of memory types over physical address ranges. However, PAT is
13 PAT allows for different types of memory attributes. The most commonly used
18 PAT APIs
100 With PAT support, a new API pgprot_writecombine is being added. So, drivers can
112 MTRR effects on PAT / non-PAT systems
116 using ioremap*() calls on x86 for both non-PAT and PAT systems. Ideally
118 be a no-op on PAT enabled systems. The region over which a arch_phys_wc_add()
119 is made, should already have been ioremapped with WC attributes or PAT entries,
130 MTRR Non-PAT PAT Linux ioremap value Effective memory type
132 Non-PAT | PAT
133 PAT
159 Over time writes to /proc/mtrr will be deprecated in favor of using PAT based
168 PAT debugging
171 With CONFIG_DEBUG_FS enabled, PAT memtype list can be examined by
175 PAT memtype list:
192 This list shows physical address ranges and various PAT settings used to
195 Another, more verbose way of getting PAT related debug messages is with
199 PAT Initialization
202 The following table describes how PAT is initialized under various
203 configurations. The PAT MSR must be updated by Linux in order to support WC
204 and WT attributes. Otherwise, the PAT MSR has the value programmed in it
205 by the firmware. Note, Xen enables WC attribute in the PAT MSR for guests.
207 MTRR PAT Call Sequence PAT State PAT MSR
209 E E MTRR -> PAT init Enabled OS
210 E D MTRR -> PAT init Disabled -
211 D E MTRR -> PAT disable Disabled BIOS
212 D D MTRR -> PAT disable Disabled -
213 - np/E PAT -> PAT disable Disabled BIOS
214 - np/D PAT -> PAT disable Disabled -
215 E !P/E MTRR -> PAT init Disabled BIOS
216 D !P/E MTRR -> PAT disable Disabled BIOS
217 !M !P/E MTRR stub -> PAT disable Disabled BIOS
226 Enabled PAT state set to enabled
227 Disabled PAT state set to disabled
228 OS PAT initializes PAT MSR with OS setting
229 BIOS PAT keeps PAT MSR with BIOS setting