GitLab

Detail:
  With this set of changes, each AMB node is now the owner of a fake DANode which is linked to a PMP.
  From a user's perspective the behaviour of AMBControl is the same as before, but rewriting it to use PMPs internally offers the following (potential) benefits:
  * Reduction in the amount of code which messes with the CAM & page tables, simplifying future work/maintenance. Some of the AMB ops (grow, shrink) now just call through to OS_ChangeDynamicArea. However all of the old AMB routines were well-optimised, so to avoid a big performance hit for common operations not all of them have been removed (e.g. mapslot / mapsome). Maybe one day these optimal routines will be made available for use by regular PMP DAs.
  * Removal of the slow Service_MemoryMoved / Service_PagesSafe handlers that had to do page list fixup after the core kernel had reclaimed/moved pages. Since everything is a PMP, the kernel will now deal with this on behalf of AMB.
  * Removal of a couple of other slow code paths (e.g. Do_AMB_MakeUnsparse calls from OS_ChangeDynamicArea)
  * Potential for more flexible mapping of application space in future, e.g. sparse allocation of memory to the wimp slot
  * Simpler transition to an ASID-based task swapping scheme on ARMv6+?
  Other changes of note:
  * AMB_LazyMapIn switch has been fixed up to work correctly (i.e. turning it off now disables lazy task swapping and all associated code instead of producing a build error)
  * The DANode for the current app should be accessed via the GetAppSpaceDANode macro. This will either return the current AMB DANode, or AppSpaceDANode (if e.g. pre-Wimp). However be aware that AppSpaceDANode retains the legacy behaviour of having a base + size relative to &0, while the AMB DANodes (identifiable via the PMP flag) are sane and have their base + size relative to &8000.
  * Mostly-useless DebugAborts switch removed
  * AMBPhysBin (page number -> phys addr lookup table) removed. Didn't seem to give any tangible performance benefit, and was imposing hidden restrictions on memory usage (all phys RAM fragments in PhysRamTable must be multiple of 512k). And if it really was a good optimisation, surely it should have been applied to all areas of the kernel, not just AMB!
  Other potential future improvements:
  * Turn the fake DANodes into real dynamic areas, reducing the amount of special code needed in some places, but allow the DAs to be hidden from OS_DynamicArea 3 so that apps/users won't get too confused
  * Add a generic abort trapping system to PMPs/DAs (lazy task swapping abort handler is still a special case)
  File changes:
  - s/ARM600, s/VMSAv6, s/ExtraSWIs - Remove DebugAborts
  - s/ArthurSWIs - Remove AMB service call handler dispatch
  - s/ChangeDyn - AMB_LazyMapIn switch fixes. Add alternate internal entry points for some PMP ops to allow the DANode to be specified (used by AMB)
  - s/Exceptions - Remove DebugAborts, AMB_LazyMapIn switch fixes
  - s/Kernel - Define GetAppSpaceDANode macro, AMB_LazyMapIn switch fix
  - s/MemInfo - AMB_LazyMapIn switch fixes
  - s/AMBControl/AMB - Update GETs
  - s/AMBControl/Memory - Remove block size quantisation, AMB_BlockResize (page list blocks are now allocated by PMP code)
  - s/AMBControl/Options - Remove PhysBin definitions, AMBMIRegWords (moved to Workspace file), AMB_LimpidFreePool switch. Add AMB_Debug switch.
  - s/AMBControl/Workspace - Update AMBNode to contain an embedded DANode. Move AMBMIRegWords here from Options file.
  - s/AMBControl/allocate - Fake DA node initialisation
  - s/AMBControl/deallocate - Add debug output
  - s/AMBControl/growp, growshrink, mapslot, mapsome, shrinkp - Rewrite to use PMP ops where possible, add debug output
  - s/AMBControl/main - Remove PhysBin initialisation. Update the enumerate/mjs_info call.
  - s/AMBControl/memmap - Low-level memory mapping routines updated or rewritten as appropriate.
  - s/AMBControl/readinfo - Update to cope with DANode
  - s/AMBControl/service - Remove old service call handlers
  - s/AMBControl/handler - DA handler for responding to PMP calls from OS_ChangeDynamicArea; just calls through to growpages/shrinkpages as appropriate.
Admin:
  Tested on pretty much everything currently supported


Version 5.66. Tagged as 'Kernel-5_66'

Detail:
  Lots of changes since last version, at least the following:
  * Updated OS timestamp, removed alpha status
  * Negative INKEY OS version changed to &AA
  * GraphicsV is now alocated vector number &2A
  * ROM moved up to &FC000000
  * Max application slot increased to 512 Mbytes (for now)
  * Max size of RMA increased to 256 Mbytes
  * RMA is now first-created dynamic area (so it gets lowest address after
    top of application slot)
  * OS_Memory 10 reimplemeted
  * New OS_ReadSysInfo 6 values 18-22 added
  * OS_ReadSysInfo 8 gains flag bit to indicate soft power-off
  * Misc internal top-bit-set-address fixes
  * *ChangeDynamicArea can take sizes in megabytes or gigabytes
  * Magic word "&off" in R0 passed to OS_Reset powers down if possible
  * Added acceleration: block copy; CLS; text window scroll up; rectangle
    fill
  * Disabled LED flashing in page mode (liable to crash)
  * Masked sprite plot and VDU 5 text avoids reading the screen if possible
  * Framestore made USR mode accessible
  * Fix for VDU 5,127 bug - now relies on font definitions being in extreme
    quarters of memory, rather than bottom half
  * Allocated 64-bit OS_Convert... SWIs
  * IIC errors use allocated error numbers
  * Looks for Dallas RTC before Philips RTC because we're using a Philips
    NVRAM device with the same ID
  * Fix to bug that meant the oscillator in the Dallas RTC wasn't enabled
  * Default mouse type (USB) changed to allocated number
  * Ram disc max size increased to 128 Mbytes (Ursula merge) and made
    cacheable for StrongARMs (not XScale)
  * Branch through zero handler now works in USR mode, by use of a
    trampoline in the system stack to allow PC-relative register storage
  * Address exception handler changed to not use 0 as workspace
  * OS_Memory 13 extended to allow specification of cacheability and access
    privileges
  * Added OS_Memory 16 to return important memory addresses
  * RISCOS_MapInIO() takes cacheable flag in bit 3, access permissions in
    bits 10 and 11, doubly-mapped flag in bit 20, and access permissions
    specified flag in bit 21
  * Bug fix in last version for application abort handlers didn't quite
    work; register shuffle required
  * "Module is not 32-bit compatible" error now reports the module name
  * Default configured language changed from 10 to 11 (now Desktop again)

Version 5.35, 4.79.2.51. Tagged as 'Kernel-5_35-4_79_2_51'

Version 5.35, 4.79.2.12. Tagged as 'Kernel-5_35-4_79_2_12'

more use of ARMops in page manipulation, change register usage of ARmops tested by kernel boot to star prompt only

Version 5.35, 4.79.2.11. Tagged as 'Kernel-5_35-4_79_2_11'