>From [EMAIL PROTECTED] Tue Aug 8 05:20:47 2000
>Joerg Schilling wrote:
>>
>> Hi all,
>>
>> from a bugreport that I got ysterday, I must assume that
>> the Linux sg driver only checks for kernel memory if more than 32 KB
>> is requested for DMA.
>Perhaps you could forward me a copy (or translation) of
>the bug report. As for your assumption, the sg driver
>attempts to use scatter gather for reserved buffer
>sizes greater than 32 KB. Kernel memory is "checked"
>(i.e. that the allocation was successful) in all cases.
This is the report:
i need help with cdrecord
i use version cdrecord1.9a01 and it works perfect
now i installed version 1.9 final and it crashes my system :(
i'm using scsi controller AHA1540 and Plextor PX-W124TS
when i type 'cdrecord -scanbus' i get this message:
BAD SEGMENT LIST SUPLIED TO AHA1542.C (1, 0)
0:c0660000 1 0
CPTR c0cf0000:08 00 00 00 08 00 2a 14 07 07 73 6f 29 23 16 0d 01 00<0>KERNEL
PANIC
My system: RedHat 6.2, Kernel 2.2.14
drivers for AHA are compiled like modules
>
>> It seems that newer cdrtools versions that try to use this new
>> feature will cause a system panic.
>Using scatter gather is a new and painful experience for
>some adapters drivers. See the faq on sg's web site:
>http://www.torque.net/sg
>for some known combinations that cause problems (and
>what can/has been done). Most failures I have seen result
>in an oops (i.e. system panic).
Note that the concept of the driver system should be changed in a way
that no leaf (target) driver need to know about scatter gather.
THis would make things a lot easier. The code should be inside the
host adapter driver for the specific HW.
>> If other people notice similar problems, I will need to disable this
>> feature until the driver is stable enough for production use.
>How is the feature disabled?
As I already wrot in this list: I man change libscg so that is does not
use more than 32 KB until it is clear when it works....
>> PLease tell me whether you could use cdrecord-1.9 & 1.10alpha
>> with ISA SCSI adapters. NOte that only cdda2wav & readcd will
>> try to transfer more than 63 KB which seems to be the hard limit
>> for ISA Hardware.
>By choosing 32 KB as the maximum element size in a scatter
>gather list the problems that some ISA adapters have with
>the 64 KB limit on a _single_ transfer should be avoided.
>This assumes that the adapters safely handle scatter gather
>(when their configuration indicates they support it).
So if this was implemented without bug, it should be possible
to get more then 63k in a ISA device?
>SANE 1.0.2 increased its default reserve buffer size from 32 KB
>to 128 KB earlier in the year and similar types of problems
>began to arise. Nearly all the patches to sg in the last 4
>months have been addressing scatter gather problems with
>ISA adapters.
Cdrecord uses a default transfer size of 63k because some drives
create problems when using more, readcd uses a default size of 256k
and cdda2wav uses a default size of 176400 bytes. These values never
changed the last three years. However they are reduced based on
what libscg returns as the current limit.
J�rg
EMail:[EMAIL PROTECTED] (home) J�rg Schilling D-13353 Berlin
[EMAIL PROTECTED] (uni) If you don't have iso-8859-1
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URL: http://www.fokus.gmd.de/usr/schilling ftp://ftp.fokus.gmd.de/pub/unix
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