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author | njl <njl@FreeBSD.org> | 2004-07-15 16:47:31 +0000 |
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committer | njl <njl@FreeBSD.org> | 2004-07-15 16:47:31 +0000 |
commit | c9b72f6bbfe07882de4c1ff97b23d8419bb01672 (patch) | |
tree | c9f3eeffe6d7e4e4b1e60450f34997b2187c1f74 /share/man/man4 | |
parent | 43c55237f6d696d68af0e0d8a16801a117828c94 (diff) | |
download | FreeBSD-src-c9b72f6bbfe07882de4c1ff97b23d8419bb01672.zip FreeBSD-src-c9b72f6bbfe07882de4c1ff97b23d8419bb01672.tar.gz |
Add a few comments about ACPI probing.
Diffstat (limited to 'share/man/man4')
-rw-r--r-- | share/man/man4/fdc.4 | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/share/man/man4/fdc.4 b/share/man/man4/fdc.4 index 2293cf1..976885d 100644 --- a/share/man/man4/fdc.4 +++ b/share/man/man4/fdc.4 @@ -27,7 +27,7 @@ .\" .\" $FreeBSD$ .\" -.Dd December 16, 2001 +.Dd July 15, 2004 .Dt FDC 4 .Os .Sh NAME @@ -60,7 +60,8 @@ can be handled. Floppy disk controllers can connect up to four drives each. The .Nm -driver can currently handle up to two drives per controller. +driver can currently handle up to two drives per controller (or four +drives on ACPI). Upon driver initialization, an attempt is made to find out the type of the floppy controller in use. @@ -153,15 +154,18 @@ Same as type 5, available for compatibility with some BIOSes .El .Pp On IA32 architectures, the drive type can be specified as 0 for the -first two drives. +drives. In that case, the CMOS configuration memory will be consulted to obtain the value for that drive. +The ACPI probe automatically determines these values via the _FDE and +_FDI methods, but this can be overriden by specifying a drive type hint. .Pp Normally, each configured drive will be probed at initialization time, using a short seek sequence. This is intended to find out about drives that have been configured but are actually missing or otherwise not responding. +(The ACPI probe method does not perform this seek.) In some environments (like laptops with detachable drives), it might be desirable to bypass this drive probe, and pretend a drive to be there so the driver autoconfiguration will @@ -317,7 +321,7 @@ Returns the floppy disk drive type. Third argument is a pointer to .Vt "enum fd_drivetype" . This type is the same as being used in the per-drive configuration -flags, or in the CMOS configuration data on IA32 systems. +flags, or in the CMOS configuration data or ACPI namespace on IA32 systems. .El .Sh FILES .Bl -tag -width ".Pa /dev/fd*" -compact |