[mythtv-users] Re: Debian Package docs

[Ray Olszewski]

At 02:00 AM 5/6/2003 -0400, Craig Longman wrote:
[...]
>one other point about the debian kernels.  i did recompile the kernel i'm 
>currently running, so i don't know if it was my fault or not, but the dma 
>is not activated by default.  also, the ide mode defaults to 33MHz, both 
>are quite detrimental to performance, especially on non-hardware 
>encoders.  is this the case for packages kernels also?  if so, some 
>mention of hdparms with a link might be a good idea.  i'm trying to figure 
>out why my lilo commands to force 66MHz and hda/b into dma aren't working, 
>once i figure that out, i'll send it to you incase someone else has the 
>same trouble.

First, whether DMA is activated "by default" or not in a custom-compiled 
Debian kernel depends on 2 things:

1. If you selected that option in kernel configuration.
2. If the kernel supports your IDE chipset.

Check #1 in the "make menuconfig" setup menu under:
         IDE, ATA and ATAPI Block devices
                 Use PCI DMA by default when available

For #2, see if you've enabled your motherboard's IDE chipset in the same 
("DE, ATA and ATAPI Block devices") menu. If you haven't, the kernel will 
disregard the above setting, viewing DMA as "not available". You *can* 
force DMA on in these cases using hdparm the usual way.

Second, look in /var/log/dmesg for information about how the ide driver is 
determining the pio bus speed (I assume this is the 33 MHz "ide mode" you 
refer to, and not the UDMA speed). I *think* it gets this from the BIOS, so 
... are you sure your BIOS supports 66 MHz?

Pre-compiled Debian kernels (the ones I've tried, anyway ... a small 
sample) enable the "use DMA if available" option. I've never checked how 
they probe or set the ide bus speed.