We're working on a project that requires a two megabytes block of
contiguous memory in kernel space. Although it is well documented that
memory can be reserved by using mem=xx arguments during boot time, it is
unclear (to me) as to how a driver can automatically detect the size of
the said reserved block.
At this moment I am 'cheating' by inserting a global variable to save a
copy of total_memory before it gets replaced by __max_memory in
arch/ppc/mm/init.c so that the saved total_memory (containing the real
physical memory size passed in from boot block) is available to my
driver. But I can't help but to feel there has to be a better way to
determine the reserved buffer size. Is there something else that will do
this without having to modify the kernel?
Any comment is appreciated.
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
Another way to allocate physically contiguous memory in 2.4 is to use
the alloc_bootmem function. It has to be called during kernel
initialization, though.
-Jim Lewis
-----Original Message-----
From: owner-linuxppc-embedded@lists.linuxppc.org
[mailto:owner-linuxppc-embedded@lists.linuxppc.org]On
Behalf Of David C.
Chiu
Sent: Friday, February 22, 2002 6:43 PM
To: linuxppc-embedded@lists.linuxppc.org
Subject: Memory Pre-allocation (mem=xxx)
We're working on a project that requires a two megabytes block of
contiguous memory in kernel space. Although it is well
documented that
memory can be reserved by using mem=xx arguments during
boot time, it is
unclear (to me) as to how a driver can automatically detect
the size of
the said reserved block.
At this moment I am 'cheating' by inserting a global
variable to save a
copy of total_memory before it gets replaced by __max_memory in
arch/ppc/mm/init.c so that the saved total_memory
(containing the real
physical memory size passed in from boot block) is available to my
driver. But I can't help but to feel there has to be a better way to
determine the reserved buffer size. Is there something else
that will do
this without having to modify the kernel?
Any comment is appreciated.
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/