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x86/pci-dma: remove the experimental forcesac boot option

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Limiting the dma mask to avoid PCI (pre-PCIe) DAC cycles while paying
the huge overhead of an IOMMU is rather pointless, and this seriously
gets in the way of dma mapping work.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Christoph Hellwig
2018-04-27 09:13:24 +02:00
parent 84564d1c76
commit 06e9552f5f
5 changed files with 6 additions and 30 deletions
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5
drivers/net/ethernet/sfc/falcon/efx.c
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@@ -1242,9 +1242,8 @@ static int ef4_init_io(struct ef4_nic *efx)
pci_set_master(pci_dev);
/* Set the PCI DMA mask. Try all possibilities from our
* genuine mask down to 32 bits, because some architectures
* (e.g. x86_64 with iommu_sac_force set) will allow 40 bit
/* Set the PCI DMA mask. Try all possibilities from our genuine mask
* down to 32 bits, because some architectures will allow 40 bit
* masks event though they reject 46 bit masks.
*/
while (dma_mask > 0x7fffffffUL) {