Kernel Panic: too few segs for DMA mapping increase AHC_NSEG

[Marco Berizzi]

Hi everybody.

I have just upgraded my PC from 768MB RAM to 1GB.
I have recompiled the kernel (2.4.14) for hi mem support (4GB).

Now it's appening a very strange behaviour.
I have several file system on the same disk (vfat file system). I have
compiled vfat driver as a module. So before try to mount I must issue a
'modprobe vfat'. I'm using Slackware 8.0. modutils version is 2.4.6

Then if I try to copy a file from that filesystem to the root filesystem
I get this error:

Kernel panic: too few segs for DMA mappings increase AHC_NSEG

Usually this is the procedure:

root login
modprobe vfat
mount /dev/sda2 /mnt   (to mount the fat partition)
cd /usr/src
cp /mnt/linux/kernel/linux-2.2.20.tar.bz2 . (I want to copy kernel
source tarball from the vfat partition to /usr/src)
CRASH..........

My MB is ABIT KT7A (bios rev ID 65  11/07/2001). Two 512 MB SDRAM
(takei).
Other HW: AHA 39160, SCSI IBM HD DDYS 18130, Matrox G450.
gcc version 2.95.3, binutils 2.10.91.0.4 (***not the original slack
8.0***, I have downgraded it for Oracle 9i)

If I compile a kernel without hi mem support all is fine.