X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=qemu%2Froms%2Fipxe%2Fsrc%2Farch%2Fi386%2Finclude%2Frealmode.h;fp=qemu%2Froms%2Fipxe%2Fsrc%2Farch%2Fi386%2Finclude%2Frealmode.h;h=dafc5a32add40741a8dec3944032a69b6d5b4763;hb=e44e3482bdb4d0ebde2d8b41830ac2cdb07948fb;hp=0000000000000000000000000000000000000000;hpb=9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00;p=kvmfornfv.git diff --git a/qemu/roms/ipxe/src/arch/i386/include/realmode.h b/qemu/roms/ipxe/src/arch/i386/include/realmode.h new file mode 100644 index 000000000..dafc5a32a --- /dev/null +++ b/qemu/roms/ipxe/src/arch/i386/include/realmode.h @@ -0,0 +1,127 @@ +#ifndef REALMODE_H +#define REALMODE_H + +#include +#include +#include + +/* + * Data structures and type definitions + * + */ + +FILE_LICENCE ( GPL2_OR_LATER ); + +/* + * Declaration of variables in .data16 + * + * To place a variable in the .data16 segment, declare it using the + * pattern: + * + * int __data16 ( foo ); + * #define foo __use_data16 ( foo ); + * + * extern uint32_t __data16 ( bar ); + * #define bar __use_data16 ( bar ); + * + * static long __data16 ( baz ) = 0xff000000UL; + * #define baz __use_data16 ( baz ); + * + * i.e. take a normal declaration, add __data16() around the variable + * name, and add a line saying "#define __use_data16 ( ) + * + * You can then access them just like any other variable, for example + * + * int x = foo + bar; + * + * This magic is achieved at a cost of only around 7 extra bytes per + * group of accesses to .data16 variables. When using KEEP_IT_REAL, + * there is no extra cost. + * + * You should place variables in .data16 when they need to be accessed + * by real-mode code. Real-mode assembly (e.g. as created by + * REAL_CODE()) can access these variables via the usual data segment. + * You can therefore write something like + * + * static uint16_t __data16 ( foo ); + * #define foo __use_data16 ( foo ) + * + * int bar ( void ) { + * __asm__ __volatile__ ( REAL_CODE ( "int $0xff\n\t" + * "movw %ax, foo" ) + * : : ); + * return foo; + * } + * + * Variables may also be placed in .text16 using __text16 and + * __use_text16. Some variables (e.g. chained interrupt vectors) fit + * most naturally in .text16; most should be in .data16. + * + * If you have only a pointer to a magic symbol within .data16 or + * .text16, rather than the symbol itself, you can attempt to extract + * the underlying symbol name using __from_data16() or + * __from_text16(). This is not for the faint-hearted; check the + * assembler output to make sure that it's doing the right thing. + */ + +/** + * Copy data to base memory + * + * @v dest_seg Destination segment + * @v dest_off Destination offset + * @v src Source + * @v len Length + */ +static inline __always_inline void +copy_to_real ( unsigned int dest_seg, unsigned int dest_off, + void *src, size_t n ) { + copy_to_user ( real_to_user ( dest_seg, dest_off ), 0, src, n ); +} + +/** + * Copy data to base memory + * + * @v dest Destination + * @v src_seg Source segment + * @v src_off Source offset + * @v len Length + */ +static inline __always_inline void +copy_from_real ( void *dest, unsigned int src_seg, + unsigned int src_off, size_t n ) { + copy_from_user ( dest, real_to_user ( src_seg, src_off ), 0, n ); +} + +/** + * Write a single variable to base memory + * + * @v var Variable to write + * @v dest_seg Destination segment + * @v dest_off Destination offset + */ +#define put_real( var, dest_seg, dest_off ) \ + copy_to_real ( (dest_seg), (dest_off), &(var), sizeof (var) ) + +/** + * Read a single variable from base memory + * + * @v var Variable to read + * @v src_seg Source segment + * @v src_off Source offset + */ +#define get_real( var, src_seg, src_off ) \ + copy_from_real ( &(var), (src_seg), (src_off), sizeof (var) ) + +/* + * REAL_CODE ( asm_code_str ) + * + * This can be used in inline assembly to create a fragment of code + * that will execute in real mode. For example: to write a character + * to the BIOS console using INT 10, you would do something like: + * + * __asm__ __volatile__ ( REAL_CODE ( "int $0x16" ) + * : "=a" ( character ) : "a" ( 0x0000 ) ); + * + */ + +#endif /* REALMODE_H */