Messages in this thread | | | Date | Wed, 25 Feb 2004 05:18:17 -0800 | From | William Lee Irwin III <> | Subject | Re: PRD_ENTRIES is 256 |
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On Wednesday 25 of February 2004 10:53, William Lee Irwin III wrote: >> PRD_ENTRIES is specified to be precisely 256; on platforms where >> PAGE_SIZE varies from 4KB the calculation in the current expression >> defining it is inaccurate, which may cause crashes. This patch changes >> it to the constant literal 256.
On Wed, Feb 25, 2004 at 02:11:13PM +0100, Bartlomiej Zolnierkiewicz wrote: > Ok, thanks. However I cannot find 256 entries limit in any ATA document > and from looking at the code 512 entries shouldn't be a problem (?). > --bart
The numbers I'm fishing out of things say that the PRD table can't exceed 64KB in size as it can't cross a 64KB boundary and its length is specified as a 16-bit byte count, so some other method of sizing the thing may be in order. I do recall something went wrong at the time I ran into this. If I turn up where I thought the number 256 came from I'll cite it.
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