# Re: reaction to a smaller buffer size

From: Henning Meier-Geinitz (hmg-ml@gmx.de)
Date: Sat Nov 18 2000 - 13:46:53 PST

- Next message: Henning Meier-Geinitz: "Re: Patches for saned/net/scanimage/user-authorization...."
  - Previous message: Jochen Eisinger: "Re: Patches for saned/net/scanimage/user-authorization...."
  - In reply to: Oliver Neukum: "reaction to a smaller buffer size"
  - Next in thread: abel deuring: "Re: reaction to a smaller buffer size"
  - Reply: abel deuring: "Re: reaction to a smaller buffer size"
  - Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

  Hi,

  On Sat, Nov 18, 2000 at 10:11:21PM +0100, Oliver Neukum wrote:
  > Hi,
  >
  > I'd like to ask whether that check
  >
  > if (real_buffersize != wanted_buffersize)
  > {
  > DBG(1, "sanei_scsi_open: could not allocate SG buffer memory "
  > "wanted: %i got: %i\n", wanted_buffersize, real_buffersize);
  > sanei_scsi_close(*fdp);
  > return SANE_STATUS_NO_MEM;
  > }
  >
  > in sanei_scsi.c might be removed. It makes using SANE with scsi drivers
  > which don't do scatter/gather very hard.

  I don't understand this fully. With sanei_scsi_open there is no way to
  tell the backend that the buffersize is smaller than expected. What
  happens if the backend sends a bigger buffer than allowed? Is it just
  slowed down or does the SCSI call return with an error?
  sanei_scsi_open already reduces the buffer size if
  proc/sys/kernel/sg-big-buff has a lower value but the backend can't
  find out about it if I understood correctly.

  Why don't you use sanei_scsi_open_extended if it is available for your
  paltform? In this case the backend can try to get a big buffer and
  knows the actual size it is allowed to use.

  Bye,
  Henning

      --
      Source code, list archive, and docs: http://www.mostang.com/sane/
      To unsubscribe: echo unsubscribe sane-devel | mail majordomo@mostang.com

  - Next message: Henning Meier-Geinitz: "Re: Patches for saned/net/scanimage/user-authorization...."
  - Previous message: Jochen Eisinger: "Re: Patches for saned/net/scanimage/user-authorization...."
  - In reply to: Oliver Neukum: "reaction to a smaller buffer size"
  - Next in thread: abel deuring: "Re: reaction to a smaller buffer size"
  - Reply: abel deuring: "Re: reaction to a smaller buffer size"
  - Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

  This archive was generated by hypermail 2b29 : Sat Nov 18 2000 - 15:06:48 PST