From 8a168f2be5d90f972975abf0b40145a75c0231b7 Mon Sep 17 00:00:00 2001 From: dzwdz Date: Wed, 21 Jul 2021 21:35:20 +0200 Subject: syscall parameter & return value passing Sadly, sysenter on i386 limits me to only 4 arguments (so, 1 for the syscall id + 3 real args). If that turns out to be an issue I'll either just switch to interrupts, or switch to x64. --- src/init/main.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'src/init/main.c') diff --git a/src/init/main.c b/src/init/main.c index cb3fa1d..6c4ccc3 100644 --- a/src/init/main.c +++ b/src/init/main.c @@ -1,15 +1,15 @@ #include -void _syscall(); +int _syscall(int, int, int, int); int main() { - _syscall(); + uint8_t color = _syscall(1, 2, 3, 4); // change the colors of VGA text // doesn't require a lot of code, but still shows that it's working uint8_t *vga = (void*) 0xB8000; for (int i = 0; i < 80 * 25; i++) - vga[(i << 1) + 1] = 0x4e; + vga[(i << 1) + 1] = color; // try to mess with kernel memory uint8_t *kernel = (void*) 0x100000; -- cgit v1.2.3