diff options
Diffstat (limited to 'doc/supplements/sparc/memmodel.texi')
| -rw-r--r-- | doc/supplements/sparc/memmodel.texi | 119 |
1 files changed, 0 insertions, 119 deletions
diff --git a/doc/supplements/sparc/memmodel.texi b/doc/supplements/sparc/memmodel.texi deleted file mode 100644 index 1b96bebccf..0000000000 --- a/doc/supplements/sparc/memmodel.texi +++ /dev/null @@ -1,119 +0,0 @@ -@c -@c COPYRIGHT (c) 1988-1998. -@c On-Line Applications Research Corporation (OAR). -@c All rights reserved. -@c -@c $Id$ -@c - -@ifinfo -@node Memory Model, Memory Model Introduction, Calling Conventions User-Provided Routines, Top -@end ifinfo -@chapter Memory Model -@ifinfo -@menu -* Memory Model Introduction:: -* Memory Model Flat Memory Model:: -@end menu -@end ifinfo - -@ifinfo -@node Memory Model Introduction, Memory Model Flat Memory Model, Memory Model, Memory Model -@end ifinfo -@section Introduction - -A processor may support any combination of memory -models ranging from pure physical addressing to complex demand -paged virtual memory systems. RTEMS supports a flat memory -model which ranges contiguously over the processor's allowable -address space. RTEMS does not support segmentation or virtual -memory of any kind. The appropriate memory model for RTEMS -provided by the targeted processor and related characteristics -of that model are described in this chapter. - -@ifinfo -@node Memory Model Flat Memory Model, Interrupt Processing, Memory Model Introduction, Memory Model -@end ifinfo -@section Flat Memory Model - -The SPARC architecture supports a flat 32-bit address -space with addresses ranging from 0x00000000 to 0xFFFFFFFF (4 -gigabytes). Each address is represented by a 32-bit value and -is byte addressable. The address may be used to reference a -single byte, half-word (2-bytes), word (4 bytes), or doubleword -(8 bytes). Memory accesses within this address space are -performed in big endian fashion by the SPARC. Memory accesses -which are not properly aligned generate a "memory address not -aligned" trap (type number 7). The following table lists the -alignment requirements for a variety of data accesses: - -@ifset use-ascii -@example -@group - +--------------+-----------------------+ - | Data Type | Alignment Requirement | - +--------------+-----------------------+ - | byte | 1 | - | half-word | 2 | - | word | 4 | - | doubleword | 8 | - +--------------+-----------------------+ -@end group -@end example -@end ifset - -@ifset use-tex -@sp 1 -@tex -\centerline{\vbox{\offinterlineskip\halign{ -\vrule\strut#& -\hbox to 1.75in{\enskip\hfil#\hfil}& -\vrule#& -\hbox to 1.75in{\enskip\hfil#\hfil}& -\vrule#\cr -\noalign{\hrule} -&\bf Data Type &&\bf Alignment Requirement&\cr\noalign{\hrule} -&byte&&1&\cr\noalign{\hrule} -&half-word&&2&\cr\noalign{\hrule} -&word&&4&\cr\noalign{\hrule} -&doubleword&&8&\cr\noalign{\hrule} -}}\hfil} -@end tex -@end ifset - -@ifset use-html -@html -<CENTER> - <TABLE COLS=2 WIDTH="60%" BORDER=2> -<TR><TD ALIGN=center><STRONG>Data Type</STRONG></TD> - <TD ALIGN=center><STRONG>Alignment Requirement</STRONG></TD></TR> -<TR><TD ALIGN=center>byte</TD> - <TD ALIGN=center>1</TD></TR> -<TR><TD ALIGN=center>half-word</TD> - <TD ALIGN=center>2</TD></TR> -<TR><TD ALIGN=center>word</TD> - <TD ALIGN=center>4</TD></TR> -<TR><TD ALIGN=center>doubleword</TD> - <TD ALIGN=center>8</TD></TR> - </TABLE> -</CENTER> -@end html -@end ifset - -Doubleword load and store operations must use a pair -of registers as their source or destination. This pair of -registers must be an adjacent pair of registers with the first -of the pair being even numbered. For example, a valid -destination for a doubleword load might be input registers 0 and -1 (i0 and i1). The pair i1 and i2 would be invalid. [NOTE: -Some assemblers for the SPARC do not generate an error if an odd -numbered register is specified as the beginning register of the -pair. In this case, the assembler assumes that what the -programmer meant was to use the even-odd pair which ends at the -specified register. This may or may not have been a correct -assumption.] - -RTEMS does not support any SPARC Memory Management -Units, therefore, virtual memory or segmentation systems -involving the SPARC are not supported. - |