Re: SHMMAX, cdrecord, kernel
Xavier Montagutelli <Xavier.Montagutelli@gmm.insa-tlse.fr> writes:
> I can't use cdrecord on my alpha box, because the default value for SHMMAX
> in the kernel sources is 0x3fa000, but cdrecord needs at least 4MB
> (0x4000000).
>
> I've seen that I can change this value 'on the fly' thrue the file
> /proc/sys/kernel/shmmax. But is there a reason for setting this to the
> value of 0x3fa000, or can I change it without any risk ? Where is this
> value coming from ? (The default value on i386 is 32 MB).
I had a look at it some time ago (same problem with cdrecord).
The size of the shm segments gets calulated by the number of
adressbits available (32, because we only have intels) minus various
bits already taken up, if I understood that right. Since Alpha has
more bits available, more are taken up already for other purposes and
though there a few left from the 32 assumed adress bits.
Thats all from memory and might be completly wrong, but the size gets
calculated somewhere along that line.
May the Source be with you.
Goswin
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