From: Truxton Fulton I have a system (Biostar IDEQ210M mini-pc with a VIA chipset) which will not reboot unless a keyboard is plugged in to it. I have tried all combinations of the kernel "reboot=x,y" flags to no avail. Rebooting by any method will leave the system in a wedged state (at the "Restarting system" message). I finally tracked the problem down to the machine's refusal to fully reboot unless the keyboard controller status register had bit 2 set. This is the "System flag" which when set, indicates successful completion of the keyboard controller self-test (Basic Assurance Test, BAT). I suppose that something is trying to protect against sporadic reboots unless the keyboard controller is in a good state (a keyboard is present), but I need this machine to be headless. I found that setting the system flag (via the command byte) before giving the "pulse reset line" command will allow the reboot to proceed. The patch is simple, and I think it should be fine for everybody whether they have this type of machine or not. This affects the "hard" reboot (as done when the kernel boot flags "reboot=c,h" are used). Signed-off-by: Andrew Morton --- include/asm-i386/mach-default/mach_reboot.h | 10 +++++++++- 1 files changed, 9 insertions(+), 1 deletion(-) diff -puN include/asm-i386/mach-default/mach_reboot.h~fix-reboot-via-keyboard-controller-reset include/asm-i386/mach-default/mach_reboot.h --- 25/include/asm-i386/mach-default/mach_reboot.h~fix-reboot-via-keyboard-controller-reset Mon Aug 29 13:53:35 2005 +++ 25-akpm/include/asm-i386/mach-default/mach_reboot.h Mon Aug 29 13:53:53 2005 @@ -22,7 +22,15 @@ static inline void mach_reboot(void) for (i = 0; i < 100; i++) { kb_wait(); udelay(50); - outb(0xfe, 0x64); /* pulse reset low */ + outb(0x60, 0x64); /* write Controller Command Byte */ + udelay(50); + kb_wait(); + udelay(50); + outb(0x14, 0x60); /* set "System flag" */ + udelay(50); + kb_wait(); + udelay(50); + outb(0xfe, 0x64); /* pulse reset low */ udelay(50); } } _