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This patch comes from Dave Jiang's Linux tree, davejiang/ntb. It hasn't been accepted into Linus' tree, so I do not have an authoritative SHA1 to point at. Original commit log: ===================================================================== A hardware errata causes the NTB to hang when heavy bi-directional traffic in addition to the usage of BAR0/1 (where the registers reside, including the doorbell registers to trigger interrupts). This workaround is only available on Haswell and Broadwell platform. The workaround is to enable split BAR in the BIOS to allow the 64bit BAR4 to be split into two 32bit BAR4 and BAR5. The BAR4 shall be pointed to LAPIC region of the remote host. We will bypass the db mechanism and directly trigger the MSIX interrupts. The offsets and vectors are exchanged during transport scratch pad negotiation. The scratch pads are now overloaded in order to allow the exchange of the information. This gets around using the doorbell and prevents the lockup with additional pcode changes in BIOS. Signed-off-by: Dave Jiang <dave.jiang@intel.com> ===================================================================== Notable changes in the FreeBSD version of this patch: * The MSIX BAR is configurable, like hw.ntb.b2b_mw_idx (msix_mw_idx). The Linux version of the patch only uses BAR4. * MSIX negotiation aborts if the link goes down. Obtained from: Linux (Dual BSD/GPL driver) Sponsored by: EMC / Isilon Storage Division |
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| ntb_hw.c | ||
| ntb_hw.h | ||
| ntb_regs.h | ||