Messages in this thread | | | Subject | Re: Problem in IDE Disks cache handling in kernel 2.4.XX | From | Alan Cox <> | Date | 10 Jan 2003 11:37:52 +0000 |
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On Fri, 2003-01-10 at 09:54, Francis Verscheure wrote: > In fact for ATA/ATAPI 5 cfs_enable_2 has no meaning. The fields to test are > write cache bits in command_set_1 and cfs_enable_1. > And in both cases the FLUSH CACHE command ALWAYS EXISTS ! > The test of cfs_enable_2 must only be used for ATA/ATAPI 6 drives to use > FLUSH CACHE or FLUSH CACHE EXT in case of 48 bit addressing mode.
Thanks for the report. I need to go reread the spec before I can definitively comemnt on this.
> And it seems to me that when an IDE drive has a cache enabled wcache must be > initialized to say so ? Or you have to do a STANDY or SLEEP before APM > suspend or power off to be sure that the cache has been written to the disk.
Technically - no. In the real world its a very very good idea
> I had a look at patch 2.4.21pre3 and the code looks the same. > > And by the way how are powered off the IDE drives ? > Because a FLUSH CACHE or STANDY or SLEEP is MANDATORY before powering off the > drive with cache enabled or you will enjoy lost data
IDE disagrees with itself over this but when we get a controlled power off we do this. The same ATA5/ATA6 problem may well be present there too. I will review both
Any specific opinion Andre ?
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