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| author | Kevin O'Connor <kevin@koconnor.net> | 2013-10-26 11:56:24 -0400 |
|---|---|---|
| committer | Kevin O'Connor <kevin@koconnor.net> | 2013-10-26 11:56:24 -0400 |
| commit | c21dce35058fd55e70d1d379dd0e62ec71f187aa (patch) | |
| tree | 68d24c6853c06decb2b635aef58dab892b440c93 /README | |
| parent | 051275b2dfc315916d120a146368095bba328c69 (diff) | |
| download | seabios-hppa-c21dce35058fd55e70d1d379dd0e62ec71f187aa.zip seabios-hppa-c21dce35058fd55e70d1d379dd0e62ec71f187aa.tar.gz seabios-hppa-c21dce35058fd55e70d1d379dd0e62ec71f187aa.tar.bz2 | |
Minor - eliminate the SET_GLOBAL macro.
Remove the SET_GLOBAL macro - it is no longer used and since it was
only available in "32bit flat" mode it does not have much use.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Diffstat (limited to 'README')
| -rw-r--r-- | README | 21 |
1 files changed, 10 insertions, 11 deletions
@@ -104,23 +104,22 @@ mode instead of a segment/offset pair. Most BIOS variables are stored in global variables, the "BDA", or "EBDA" memory areas. Because this is common, three sets of helper -macros (GET/SET_GLOBAL, GET/SET_BDA, and GET/SET_EBDA) are available -to simplify these accesses. Also, an area in the 0xc0000-0xf0000 -memory range is made available for internal BIOS run-time variables -that are marked with the VARLOW attribute. These variables can then -be accessed with the GET/SET_LOW macros. +macros (GET_GLOBAL, GET/SET_BDA, and GET/SET_EBDA) are available to +simplify these accesses. Also, an area in the 0xc0000-0xf0000 memory +range is made available for internal BIOS run-time variables that are +marked with the VARLOW attribute. These variables can then be +accessed with the GET/SET_LOW macros. Global variables defined in the C code can be read in 16bit mode if the variable declaration is marked with VAR16, VARFSEG, or VAR16FIXED. The GET_GLOBAL macro will then allow read access to the variable. Global variables are stored in the 0xf000 segment. Because the f-segment is marked read-only during run-time, the 16bit code is not -permitted to change the value of 16bit variables (use of the -SET_GLOBAL macro from 16bit mode will cause a link error). Code -running in 32bit mode can not access variables with VAR16, but can -access variables marked with VARFSEG, VARLOW, VAR16FIXED, or with no -marking at all. The 32bit code can use the GET/SET_GLOBAL macros, but -they are not required. +permitted to change the value of 16bit variables. Code running in +32bit mode can not access variables with VAR16, but can access +variables marked with VARFSEG, VARLOW, VAR16FIXED, or with no marking +at all. The 32bit code can use the GET_GLOBAL macros, but they are +not required. GCC 16 bit stack limitations: |