[SeaBIOS] [PATCH 2/2] Backup and restore a20 on call32_sloppy()
Kevin O'Connor
kevin at koconnor.net
Sat Oct 11 20:16:03 CEST 2014
Previously, the a20 line would always be enabled and left on after
call32_sloppy(). The setting should really be backed up and restored
on each call.
Signed-off-by: Kevin O'Connor <kevin at koconnor.net>
---
src/stacks.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/src/stacks.c b/src/stacks.c
index 0d3eb77..b8d6e62 100644
--- a/src/stacks.c
+++ b/src/stacks.c
@@ -25,6 +25,7 @@
struct {
u8 method;
u8 cmosindex;
+ u8 a20;
u16 ss, fs, gs;
struct descloc_s gdt;
} Call32Data VARLOW;
@@ -174,6 +175,9 @@ call32_sloppy_prep(void)
inb(PORT_CMOS_DATA);
SET_LOW(Call32Data.cmosindex, cmosindex);
+ // Enable a20 and backup it's previous state
+ SET_LOW(Call32Data.a20, set_a20(1));
+
// Backup ss/fs/gs and gdt
SET_LOW(Call32Data.ss, GET_SEG(SS));
SET_LOW(Call32Data.fs, GET_SEG(FS));
@@ -201,6 +205,9 @@ call32_sloppy_post(void)
SET_SEG(FS, GET_LOW(Call32Data.fs));
SET_SEG(GS, GET_LOW(Call32Data.gs));
+ // Restore a20
+ set_a20(GET_LOW(Call32Data.a20));
+
// Restore cmos index register
outb(GET_LOW(Call32Data.cmosindex), PORT_CMOS_INDEX);
inb(PORT_CMOS_DATA);
--
1.9.3
More information about the SeaBIOS
mailing list