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Subject[PATCH] i386 bootmem restrictions
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Date
The bootmem allocator is initialised before the kernel virtual address space
has been fully established. As a result, any allocations which are made
before paging_init() has completed may point to invalid kernel addresses.
This patch notes this limitation and indicates where the allocator is
fully available.

Revision: $Rev: 572 $

Signed-off-by: Andy Whitcroft <apw@shadowen.org>

diffstat 100-ia32_bootmem
---
setup.c | 11 ++++++++++-
1 files changed, 10 insertions(+), 1 deletion(-)

diff -X /home/apw/brief/lib/vdiff.excl -rupN reference/arch/i386/kernel/setup.c current/arch/i386/kernel/setup.c
--- reference/arch/i386/kernel/setup.c 2004-08-25 12:13:32.000000000 +0100
+++ current/arch/i386/kernel/setup.c 2004-08-26 10:27:59.000000000 +0100
@@ -1350,7 +1350,12 @@ void __init setup_arch(char **cmdline_p)

/*
* NOTE: before this point _nobody_ is allowed to allocate
- * any memory using the bootmem allocator.
+ * any memory using the bootmem allocator. Although the
+ * alloctor is now initialised only the first 8Mb of the kernel
+ * virtual address space has been mapped. All allocations before
+ * paging_init() has completed must use the alloc_bootmem_low_pages()
+ * variant (which allocates DMA'able memory) and care must be taken
+ * not to exceed the 8Mb limit.
*/

#ifdef CONFIG_SMP
@@ -1358,6 +1363,10 @@ void __init setup_arch(char **cmdline_p)
#endif
paging_init();

+ /*
+ * NOTE: at this point the bootmem allocator is fully available.
+ */
+
#ifdef CONFIG_EARLY_PRINTK
{
char *s = strstr(*cmdline_p, "earlyprintk=");
-
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