76 lines
4.3 KiB
Plaintext
76 lines
4.3 KiB
Plaintext
# The OS/K Team licenses this file to you under the MIT license.
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# See the LICENSE file in the project root for more information.
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CPU device function slots:
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slot ax0 ax1 ax2 thr name desc
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0-15 - - - - (reserved) (reserved)
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16 - - - - getmaxidx rax = maximal index for a register frame
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17 - - - - getrfusage rax = number of register frames active
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18 - - - - getcuridx rax = index of the current register frame
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19 - - - - leastavail rax = least index among inactive frames, -1 if none
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20 i - - - isactive rax = is register frame #ax0 active?
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21 i - - y activate activates register frame #ax0 (filling it with 0's)
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22 i - - y deactivate deactivates register frame #ax0 (losing all its contents!)
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23 i i - y copyframe copy contents of frame #ax1 into (active) frame #ax0
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24 i i - y moveframe move frame #ax1 to (inactive) frame index #ax0
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25 i - - - switchrf switch to register frame #ax0
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26-31 - - - - (reserved) (reserved)
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32 i - - - loadargs load registers ax0-ax5 from frame #ax0
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33 i r - - loadreg rax = register #ax1 from frame #ax0
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34-47 - - - - (reserved) (reserved)
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48 i r i y storereg store ax2 into register #ax1 from frame #ax0
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49-63 - - - - (reserved) (reserved)
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64 i i - y idtadd mark E/I #ax0 as handled by register frame #ax1
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65 i - - y idtdel mark E/I #ax0 as unhandled
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66 i - - - idtquery rax = E/I #ax0 has handler? rdx = index of handling frame
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67 i - - - idtdone signals that handler for E/I #ax0 is done handling
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68+ - - - - (reserved) (reserved)
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Arguments:
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i immediate
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r register index (0=inv, 1=rip, etc...)
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Terminology:
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interrupt: asynchronous transfer of control to another RFRAME due to some device
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exception: general term for synchronous transfer of control to another RFRAME
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fault: hardware exception (slots 1-255)
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trap: software exception (slots 256-511)
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IDT slots:
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0 a handler at this slot will receive all exceptions
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1-255 hardware exceptions (see vm/except.h), OVERRIDES slot 0
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256-511 software exceptions (TRAP instruction), OVERRIDES slot 0
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512 a handler at this slot will receive all maskable hardware interrupts
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513-767 maskable hardware interrupts (see ...), OVERRIDES slot 512
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768 a handler in this slot will receive all non-maskable hardware interrupts
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769-1022 non-maskable hardware interrupts (see ...), OVERRIDES slot 768
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1023 Uncatchable exception, guarantees shutdown. Only throwable by supervisor
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via the CRASH instruction, or by the machine in case of irrecoverable failure
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A handler for some E/I must use the 'idtdone' iocall to show that it is done dealing with
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a certain E/I. If that same E/I happens again before that, the following happens:
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- if this E/I is a fault (hardware exception), but not #DBF, then a #DBF exception is thrown
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- if this E/I is #DBF (double fault), the system crashes ("triple fault")
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- if this E/I is a hardware interrupt, it is queued (*** XXX ***)
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When called, a handler will receive the number of the E/I it is handling in R12,
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and its own RFRAME ID in R13. (in particular, if exception #25 happens and there are no
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handler for it, the handler #0 that will be called will receive '25' in R12, and '0' in R13).
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R13 is the value that must be passed to the 'initdone' iocall.
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The handler will also receive the previous RFRAME ID in R14.
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R15 is also modified but its value is meaningful only to the processor.
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To return from an E/I, *after* having called 'idtdone' (using the value originally in R11),
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the handler must simply restore R14's and R15's values to what they were when the handler
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started executing, and then use the 'IRET' instruction.
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Clearing the interrupt flag prevents (and queues) maskable hardware interrupts
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Note: RFRAME #0 *cannot* handle interrupts, as a value of 0 in an IDT slot
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indicates than there are no handler for the corresponding exception/interrupt
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