From: fl0p+@andrew.cmu.edu (Frank T Lofaro) Subject: Floppy DMA, question and patch (?) Date: 14 Dec 1992 11:12:50 GMT
Is the 1MB DMA restriction in the floppy code necessary, or can
386/486's handle 16MB DMA for the floppy? I have this patch (suggested
to me in e-mail) that ups the limit to 16MB from 1MB, and it seems to
work. This patch was made using 0.98.6, but should fit into just about
anything. (its really small). I am not posting in to
comp.os.linux.announce, since I am not sure that what it does is okay.
It seems to work for me, so far... Well, here is the patch, for
kernel/blk_drv/floppy.c. Sorry, you have to cd into kernel/blk_drv after
cd'ing into the root of your source tree (I made the diff in that
directory, and since it is unofficial, and I was in a hurry, I haven't
had a chance to fix it.). Well anyway, here is the patch, for those that
want to try it. *NO GUARANTEES THAT THIS WILL WORK. IT MIGHT EVEN CRASH
YOUR SYSTEM OR DAMAGE FILES*. Hopefully, we will all hear soon if this
change is okay.
*** floppy.c.olddma Mon Dec 14 00:54:40 1992
--- floppy.c Mon Dec 14 00:55:40 1992
***************
*** 121,129 ****
/*
* The DMA channel used by the floppy controller cannot access data at
! * addresses >= 1MB
*/
! #define LAST_DMA_ADDR (0x100000 - BLOCK_SIZE)
/*
* globals used by 'result()'
--- 121,129 ----
/*
* The DMA channel used by the floppy controller cannot access data at
! * addresses >= 16MB
*/
! #define LAST_DMA_ADDR (0x1000000 - BLOCK_SIZE)
/*
* globals used by 'result()'