On 08/28/2005 06:40:04 AM, Kai Makisara wrote:
On Fri, 26 Aug 2005, Kai Makisara wrote:
> On Thu, 25 Aug 2005, Andrew Morton wrote:
>
> > Could this purely be a highmem problem? Is the zero-copy DMA feature of
> > st.c known to work OK with x86 highmem?
>
> It is _not_ known _not_ to work ;-) I.e., I have received neither any
> success nor any failure reports. I have not tested it because I don't have
> any machine with enough memory (and I have not hacked a kernel to use
> highmem with 512 MB of memory). I hope someone seeing this thread and
> using highmem with tape can comment on this subject.
>
OK. I booted my test i386 machine with highmem=384m and did some tests. I
also added a counter to st.c to count the highmem pages used for zero-copy
DMA. I could not get dd to use highmem but with tar that succeeded. No
extra messages were found in syslog during these tests.
BUT, at the same time I remembered that the system in the Bugzilla report
was Athlon64 running FC3 x86_64. The x86_64 kernel does not have highmem.
True. I do have a machine running FC4 x86_64, but it doesn't have 4G of
memory, so it doesn't do the 4G-remap that the bug report refers to.
Don't know if there is any way to make it do so (other than buy more memory).
Regards, Willem Riede.
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