Hi all,
I think I may have found a bug, and would appreciate someone taking a second look.
Processor is an Atom C2718, we're using Coreboot 4.0 and booting into Grub and Linux. I have found that making minor/trivial changes in Coreboot (such as configuring an additional pin as a GPIO, or adding a couple of extra lines of debut output) results in the processor rebooting during SeaBIOS' rtc_setup() call.
Hard power-cycles work absolutely fine. The problem only occurs after issuing the reboot command from Linux. It's worth noting that our platform doesn't reset the power supplies, so rebooting is basically a "warm" reboot. Also, our RTC isn't battery-backed. Following the reboot, the processor resets each time it reaches rtc_setup(). My best guess so far is that my trivial code changes are subtly changing the boot timing, meaning that by the time I hit the rtc_setup, I have a pending NMI.
Anyway, rtc_setup() performs several CMOS register reads/writes. The function that triggers the reset is rtc_mask(). This is the only routine in the RTC code that doesn't explicitly disable non-maskable interrupts when writing to the CMOS index register. The patch below allows everything to boot as it should.
Index: src/hw/rtc.c =================================================================== --- a/src/hw/rtc.c +++ b/src/hw/rtc.c @@ -30,7 +30,7 @@ void rtc_mask(u8 index, u8 off, u8 on) { - outb(index, PORT_CMOS_INDEX); + outb(index | NMI_DISABLE_BIT, PORT_CMOS_INDEX); u8 val = inb(PORT_CMOS_DATA); outb((val & ~off) | on, PORT_CMOS_DATA); }
Best, Tim
This email and attachments may contain privileged or confidential information intended only for the addressee(s) indicated. The sender does not waive any of its rights, privileges or protections respecting this information. If you are not the named addressee, an employee, or agent responsible for sending this message to the named addressee (or this message was received by mistake), you are not authorized to read, print, retain, copy or disseminate this message or any part of it. If received in error, please notify us immediately by e-mail, discard any paper copies and delete all electronic files of the email.
Computer viruses can be transmitted via email. The recipient should check this email and any attachments for viruses. Email transmission cannot be guaranteed to be secured or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses. The sender accepts no liability for any damage caused by any transmitted viruses or errors or omissions in the contents of this message.
Overture Networks, Inc. 637 Davis Drive, Morrisville, NC USA 27560 www.overturenetworks.com