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Add OS_Memory 19, which is intended to replace the OS_Memory 0 "make...
Jeffrey Lee authored 
Add OS_Memory 19, which is intended to replace the OS_Memory 0 "make uncacheable" feature, when used for DMA

Detail:
  Making pages uncacheable to allow them to be used with DMA can be troublesome for a number of reasons:
  * Many processors ignore cache hits for non-cacheable pages, so to avoid breaking any IRQ handlers the page table manipulation + cache maintenance must be performed with IRQs disabled, impacting the IRQ latency of the system
  * Some processors don't support LDREX/STREX to non-cacheable pages
  * In SMP setups it may be necessary to temporarily park the other cores somewhere safe, or perform some other explicit synchronisation to make sure they all have consistent views of the cache/TLB
  The above issues are most likely to cause problems when the page is shared by multiple programs; a DMA operation which targets one part of a page could impact the programs which are using the other parts.
  To combat these problems, OS_Memory 19 is being introduced, which allows DMA cache coherency/address translation to be performed without altering the attributes of the pages.
  Files changed:
  - hdr/OSMem - Add definitions for OS_Memory 19
  - s/MemInfo - Add OS_Memory 19 implementation
Admin:
  Tested on Raspberry Pi 3, iMx6


Version 5.86, 4.129.2.3. Tagged as 'Kernel-5_86-4_129_2_3'
b47fdbb1
Name Last commit Last update
..
ExportVals 32-bit Kernel.
ARMops Support for ARMv8
Copro15ops Add new ARMops. Add macros which map the ARMv7/v8 cache/TLB maintenance mnemonics (as featured in recent ARM ARMs) to MCR ops.
DBellDevice Initial SMP changes
EnvNumbers Import from cleaned 360 CD
EtherDevice Added link to Phy powerup and reset routine in EtherDevice
HALDevice Initial SMP changes
HALEntries Initial SMP changes
KernelWS Initial SMP changes
KeyWS Delete STB code
ModHand Resolve 2x header clashes
OSEntries Teach the kernel about different memory attributes
OSMem Add OS_Memory 19, which is intended to replace the OS_Memory 0 "make uncacheable" feature, when used for DMA
OSMisc Expose CLREX via OS_PlatformFeatures
OSRSI6 Add initial support for "physical memory pools"
Options Initial SMP changes
PL310 Add ARMops for PL310 L2 cache controller
PublicWS Fix HiProcVecs build. Remove old-style PublicWS definitions.
RISCOS Resync with allocations database (added symbolic names for Internet Event subreason codes)
VIDCList Reverse interlace deprecation decision
Variables Import from cleaned 360 CD
VduExt Improve Service_DisplayStatus, Service_DisplayChanged functionality
VideoDevice Update VDU HAL device for new OMAPVideo driver, fix MVA-based cache/TLB maintenance ops aborting on ARMv7, add warning to VDU driver about inconsistent state variables during screen mode changes