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Bug 56100 - RedHat 7.2 fails to enable UDMA100 for IDE.
RedHat 7.2 fails to enable UDMA100 for IDE.
Product: Red Hat Linux
Classification: Retired
Component: kernel (Show other bugs)
i686 Linux
high Severity medium
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Assigned To: Arjan van de Ven
Brock Organ
Depends On:
  Show dependency treegraph
Reported: 2001-11-12 15:34 EST by Aaron Freed
Modified: 2007-03-26 23:49 EDT (History)
1 user (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2001-11-12 15:44:20 EST
Type: ---
Regression: ---
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Verified Versions:
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oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
dmessg output detailing problem and showing sample from another machine that UDMA66/UDMA 100 *SHOULD* work.... (13.07 KB, text/plain)
2001-11-12 15:44 EST, Aaron Freed
no flags Details

  None (edit)
Description Aaron Freed 2001-11-12 15:34:10 EST
Description of Problem:

Version-Release number of selected component (if applicable):

How Reproducible:

Steps to Reproduce:
1. Install RedHat 7.2
2. Boot (Ensure MPS Spec 1.1 in Bios.  MPS 1.4 causes this Asus CUV-4X 
dual PIII 933 to hang on ISAPNP scanning for devices on boot up.)
3. Be disappointed with poor (udma-33 equivalent drive I/O performance.)

Actual Results:
Going to INIT 1 and then running hdparm -t /dev/hda or hdparm -t /dev/hdb 
produces results of 20.08 for HDA and 24.37 for HDB, which are an IBM 40 
GB ATA 100 drive and a Maxtor 100 GB ATA 100 drive respectively.

Expected Results
Disk I/O data transfer rates were expected to be in the 30 MB/sec to 60 
MB/sec range.  A number of Dell Optiplex machines at this site have UDMA 
33 controllers and manage more than 30 MB/sec.

Additional Information:

cat /proc/ide/via
----------VIA BusMastering IDE Configuration----------------
Driver Version:                     3.23
South Bridge:                       VIA vt82c686b
Revision:                           ISA 0x40 IDE 0x6
Highest DMA rate:                   UDMA100
BM-DMA base:                        0xd800
PCI clock:                          33MHz
Master Read  Cycle IRDY:            0ws
Master Write Cycle IRDY:            0ws
BM IDE Status Register Read Retry:  yes
Max DRDY Pulse Width:               No limit
-----------------------Primary IDE-------Secondary IDE------
Read DMA FIFO flush:          yes                 yes
End Sector FIFO flush:         no                  no
Prefetch Buffer:              yes                  no
Post Write Buffer:            yes                  no
Enabled:                      yes                 yes
Simplex only:                  no                  no
Cable Type:                   40w                 40w
Transfer Mode:       UDMA      UDMA       DMA      UDMA
Address Setup:       30ns      30ns      30ns      30ns
Cmd Active:          90ns      90ns      90ns      90ns
Cmd Recovery:        30ns      30ns      30ns      30ns
Data Active:         90ns      90ns      90ns      90ns
Data Recovery:       30ns      30ns      30ns      30ns
Cycle Time:          60ns      60ns     120ns      60ns
Transfer Rate:   33.3MB/s  33.3MB/s  16.5MB/s  33.3MB/s
[root@liberty1 ide]# pwd
[root@liberty1 ide]#

It seems clear from the above (as well as the attached dmesg output) that 
the maximum transfer rate is 100 MB/s, and that all I am getting is 
33.3MB/s for all drives (except the CD Burner at HDC.)
Comment 1 Arjan van de Ven 2001-11-12 15:36:54 EST
VIA controllers sometimes misdetect a udma33 cable as a udma66 cable, and as a
result we have to not trust the chipset.
You can tell the kernel you have safe cables by passing "ide0=ata66" on the
kernel commandline (edit grub.conf for that and add it to the end of the line
with vmlinuz in it)
Comment 2 Aaron Freed 2001-11-12 15:44:15 EST
Created attachment 37282 [details]
dmessg output detailing problem and showing sample from another machine that UDMA66/UDMA 100 *SHOULD* work....

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