Ingo Molnar wrote:
the patch below is a blind shot into the dark: it turns on MMIO for the
sata_nv driver. But be careful with it - this turns on a probably
totally untested mode in the driver and thus may damage your data. (It
might not even work at all because the driver might not be ready for it
- Jeff?). I'd suggest to first boot into single-user mode with all
filesystems readonly mounted.
on the low chance of this patch actually working, the interesting thing
would be to check whether the latencies occur in MMIO mode too? (if they
do then please send us the new latency traces too.)
Ingo
---------
WARNING: this may damage your data. Be careful ...
drivers/scsi/sata_nv.c | 1 +
1 files changed, 1 insertion(+)
Index: linux/drivers/scsi/sata_nv.c
===================================================================
--- linux.orig/drivers/scsi/sata_nv.c
+++ linux/drivers/scsi/sata_nv.c
@@ -280,6 +280,7 @@ static struct ata_port_info nv_port_info
.host_flags = ATA_FLAG_SATA |
/* ATA_FLAG_SATA_RESET | */
ATA_FLAG_SRST |
+ ATA_FLAG_MMIO |
ATA_FLAG_NO_LEGACY,
It won't work at all...
You have to stop talking to PCI IDE registers completely (consumes 5 PCI
BARs), and talk exclusively to the MMIO 6th PCI BAR, at non-standard
offsets and a using a proprietary DMA descriptor format [all public now
in that link I just sent].
My main workstation has one:
00:08.0 IDE interface: nVidia Corporation CK804 Serial ATA Controller (rev f3) (prog-if 85 [Master SecO PriO])
Subsystem: Hewlett-Packard Company: Unknown device 1500
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
Status: Cap+ 66Mhz+ UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort-
<MAbort- >SERR- <PERR-
Latency: 0 (750ns min, 250ns max)
Interrupt: pin A routed to IRQ 201
Region 0: I/O ports at 28e0 [size=8]
Region 1: I/O ports at 2c00 [size=4]
Region 2: I/O ports at 28e8 [size=8]
Region 3: I/O ports at 2c04 [size=4]
Region 4: I/O ports at 28c0 [size=16]
Region 5: Memory at f2103000 (32-bit, non-prefetchable) [size=4K]
Regards,
Jeff
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