[lkml]   [2001]   [May]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: alpha iommu fixes
At 1:28 PM -0700 2001-05-22, Richard Henderson wrote:
>On Tue, May 22, 2001 at 05:00:16PM +0200, Andrea Arcangeli wrote:
>> I'm also wondering if ISA needs the sg to start on a 64k boundary,
>Traditionally, ISA could not do DMA across a 64k boundary.
>The only ISA card I have (a soundblaster compatible) appears
>to work without caring for this, but I suppose we should pay
>lip service to pedantics.

64KB for 8-bit DMA; 128KB for 16-bit DMA. It's a limitation of the
legacy third-party-DMA controllers, which had only 16-bit address
registers (the high part of the address lives in a non-counting
register). This doesn't apply to bus-master DMA, just the legacy
(8237) stuff. There was also a 24-bit address limitation.
/Jonathan Lundell.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 12:53    [W:0.341 / U:0.012 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site