Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Browse files
Browse the repository at this point in the history
[rng] Check for functioning RTC interrupt
On some platforms (observed in a small subset of Microsoft Azure (Hyper-V) virtual machines), the RTC appears to be incapable of generating an interrupt via the legacy PIC. The RTC status registers show that a periodic interrupt has been asserted, but the PIC IRR shows that IRQ8 remains inactive. On such systems, iPXE will currently freeze during the "iPXE initialising devices..." message. Work around this problem by checking that RTC interrupts are being raised before returning from rtc_entropy_enable(). If no interrupt is seen within 100ms, then we assume that the RTC interrupt mechanism is broken. In these circumstances, iPXE will continue to initialise but any subsequent attempt to generate entropy will fail. In particular, HTTPS connections will fail with an error indicating that no entropy is available. Signed-off-by: Michael Brown <mcb30@ipxe.org>
- Loading branch information
Showing
2 changed files
with
57 additions
and
0 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters