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Date: Sat, 16 Apr 2011 15:08:04 +0800
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To: linux-kernel@vger.kernel.org
Subject: alloc memory for massive legacy ptys
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Hi all:

In a rare condition, I need to alloc massive legacy ptys on SLES 9 SP4,
kernel 2.6.5-7.308-smp.

I noticed the limit number of legacy ptys was 10922, due to the kmalloc
128kb limit. 10922 * 3 * sizeof (void *) was 8 bytes lesser than 128kb
on 32bit system.

I tried to use vmalloc instead of kmalloc in tty_register_driver(). My
system was able to boot, but I'm not sure if it was safely to do this,
since vmalloc don't guarant the phy memory were contiguous, and I don't
know the pty driver memory requirements neither.