From: None <email@example.com>
Date: 02/15/1999 23:40:51
I've attached a little diff to the GENERIC kernel config file as shipped
with the i386 snapshot of Feb 1st, 1999. As it stands the explanation
for the PCI-IDE flags got bits and bytes a bit mixed up. Hopefully, my
little rewrite will make flags a bit easier to understand.
--- GENERIC.bak Mon Feb 15 23:20:37 1999
+++ GENERIC Mon Feb 15 23:28:48 1999
@@ -322,9 +322,9 @@
uk* at scsibus? target ? lun ? # SCSI unknown
-# IDE and Related Devices
-# PCI IDE controllers (CMD tech's PCI0640, Intel's PIIx, ...).
-# The 0x0001 flag force the driver to use DMA, even if the driver doesn't know
+# IDE and related devices
+# PCI IDE controllers (CMD Tech's PCI0640, Intel's PIIx, ...)
+# The 0x0001 flag forces the driver to use DMA, even if the driver doesn't know # how to set up DMA modes for this chip. This may work, or may cause
# a machine hang with some controllers.
pciide* at pci ? dev ? function ? flags 0x0000
@@ -339,15 +339,17 @@
wdc0 at isa? port 0x1f0 irq 14
wdc1 at isa? port 0x170 irq 15
-# IDE drives.
+# IDE drives
# Flags are used only with controlers that support DMA operations
# and mode settings (e.g. some pciide controllers)
-# The first 4 bytes of the flags define the PIO mode to use, the
-# second DMA mode and the third UltraDMA mode. For each group of 4 bytes,
-# the 3 lower define the mode to use, and the last one must be 1 for the
-# setting to be used. For DMA and UDMA, 0xf means 'disable'.
-# 0x0fac means 'use PIO mode 4 DMA mode 2, disable UltraDMA'.
-# 0x0000 means "use whatever the drive claims to support.
+# The lowest order four bits of the flags define the PIO mode to use, the
+# next set of four bits the DMA mode and the third set the UltraDMA mode.
+# For each set of four bits, the 3 lower bits define the mode to use, and
+# the last bit must be 1 for this setting to be used.
+# For DMA and UDMA, 0xf (1111) means 'disable'.
+# 0x0fac means 'use PIO mode 4, DMA mode 2, disable UltraDMA'.
+# (0xc=1100, 0xa=1010, 0xf=1111)
+# 0x0000 means "use whatever the drive claims to support".
wd* at wdc? channel ? drive ? flags 0x0000
wd* at pciide? channel ? drive ? flags 0x0000