Special handling for DMA memory?

Matthias Sattler (m_sattle@informatik.uni-kl.de)
Mon, 4 Mar 1996 18:32:36 +0100 (MET)


Hiho

Do we need a special handling for DMA-able memory especially when modules
are used? I often try to insmod the scsi tape module, but all I get is:

Detected scsi tape st0 at scsi0, channel 0, id 3, lun 0
st: Can't allocate new tape buffer (nbr 0).
Can't continue without at least one tape buffer.

There is enough memory free, but no DMA memory (especially if the memory
is requested GFP_ATOMIC). Similar things happen with the floppy module as
well.

I suggest a pool of reserved DMA memory that is only used if the memory is
requested GFP_DMA and the request would fail otherwise. Maybe its size
should be set via a kernel parameter.

Matthias

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