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diff --git a/doc/supplements/i386/bsp.t b/doc/supplements/i386/bsp.t deleted file mode 100644 index c15fb24835..0000000000 --- a/doc/supplements/i386/bsp.t +++ /dev/null @@ -1,109 +0,0 @@ -@c -@c COPYRIGHT (c) 1988-1998. -@c On-Line Applications Research Corporation (OAR). -@c All rights reserved. -@c -@c $Id$ -@c - -@chapter Board Support Packages - -@section Introduction - -An RTEMS Board Support Package (BSP) must be designed to support a -particular processor and target board combination. This chapter presents a -discussion of i386 specific BSP issues. For more information on developing -a BSP, refer to the chapter titled Board Support Packages in the RTEMS -Applications User's Guide. - -@section System Reset - -An RTEMS based application is initiated when the i386 -processor is reset. When the i386 is reset, - -@itemize @bullet - -@item The EAX register is set to indicate the results of the processor's -power-up self test. If the self-test was not executed, the contents of -this register are undefined. Otherwise, a non-zero value indicates the -processor is faulty and a zero value indicates a successful self-test. - -@item The DX register holds a component identifier and revision level. DH -contains 3 to indicate an i386 component and DL contains a unique revision -level indicator. - -@item Control register zero (CR0) is set such that the processor is in real -mode with paging disabled. Other portions of CR0 are used to indicate the -presence of a numeric coprocessor. - -@item All bits in the extended flags register (EFLAG) which are not -permanently set are cleared. This inhibits all maskable interrupts. - -@item The Interrupt Descriptor Register (IDTR) is set to point at address -zero. - -@item All segment registers are set to zero. - -@item The instruction pointer is set to 0x0000FFF0. The first instruction -executed after a reset is actually at 0xFFFFFFF0 because the i386 asserts -the upper twelve address until the first intersegment (FAR) JMP or CALL -instruction. When a JMP or CALL is executed, the upper twelve address -lines are lowered and the processor begins executing in the first megabyte -of memory. - -@end itemize - -Typically, an intersegment JMP to the application's initialization code is -placed at address 0xFFFFFFF0. - -@section Processor Initialization - -This initialization code is responsible for initializing all data -structures required by the i386 in protected mode and for actually entering -protected mode. The i386 must be placed in protected mode and the segment -registers and associated selectors must be initialized before the -initialize_executive directive is invoked. - -The initialization code is responsible for initializing the Global -Descriptor Table such that the i386 is in the thirty-two bit flat memory -model with paging disabled. In this mode, the i386 automatically converts -every address from a logical to a physical address each time it is used. -For more information on the memory model used by RTEMS, please refer to the -Memory Model chapter in this document. - -Since the processor is in real mode upon reset, the processor must be -switched to protected mode before RTEMS can execute. Before switching to -protected mode, at least one descriptor table and two descriptors must be -created. Descriptors are needed for a code segment and a data segment. ( -This will give you the flat memory model.) The stack can be placed in a -normal read/write data segment, so no descriptor for the stack is needed. -Before the GDT can be used, the base address and limit must be loaded into -the GDTR register using an LGDT instruction. - -If the hardware allows an NMI to be generated, you need to create the IDT -and a gate for the NMI interrupt handler. Before the IDT can be used, the -base address and limit for the idt must be loaded into the IDTR register -using an LIDT instruction. - -Protected mode is entered by setting thye PE bit in the CR0 register. -Either a LMSW or MOV CR0 instruction may be used to set this bit. Because -the processor overlaps the interpretation of several instructions, it is -necessary to discard the instructions from the read-ahead cache. A JMP -instruction immediately after the LMSW changes the flow and empties the -processor if intructions which have been pre-fetched and/or decoded. At -this point, the processor is in protected mode and begins to perform -protected mode application initialization. - -If the application requires that the IDTR be some value besides zero, then -it should set it to the required value at this point. All tasks share the -same i386 IDTR value. Because interrupts are enabled automatically by -RTEMS as part of the initialize_executive directive, the IDTR MUST be set -properly before this directive is invoked to insure correct interrupt -vectoring. If processor caching is to be utilized, then it should be -enabled during the reset application initialization code. The reset code -which is executed before the call to initialize_executive has the following -requirements: - -For more information regarding the i386s data structures and their -contents, refer to Intel's 386 Programmer's Reference Manual. - |