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Gen8 and prior Proliant systems supported the "CRU" interface to firmware. This interfaces allows linux to "call back" into firmware to source the cause of an NMI. This feature isn't fully utilized as the actual source of the NMI isn't printed, the driver only indicates that the source couldn't be determined when the call fails. With the advent of Gen9, iCRU replaces the CRU. The call back feature is no longer available in firmware. To be compatible and not attempt to call back into firmware on system not supporting CRU, the SMBIOS table is consulted to determine if it is safe to make the call back or not. This results in about half of the driver code being devoted to either making CRU calls or determing if it is safe to make CRU calls. As noted, the driver isn't really using the results of the CRU calls. Furthermore, as a consequence of the Spectre security issue, the BIOS/EFI calls are being wrapped into Spectre-disabling section. Removing the call back in hpwdt_pretimeout assists in this effort. As the CRU sourcing of the NMI isn't required for handling the NMI and there are security concerns with making the call back, remove the legacy (pre Gen9) NMI sourcing and the DMI code to determine if the system had the CRU interface. Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com> Acked-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.