Cc: Yinghai Lu <yhlu.kernel@...>, Ingo Molnar <mingo@...>, H. Peter Anvin <hpa@...>, Andrew Morton <akpm@...>, linux-kernel@vger.kernel.org <linux-kernel@...>
This patch is still required to make Xen boot with the e820 changes:
Subject: xen: boot via i386_start_kernel to get early reservations
Boot Xen via i386_start_kernel so that all the early reservations are
made properly; without these, it will start using the kernel and
pagetables as early heap memory, which is a bit suboptimal.
One tricky part is that reserve_early() will just panic if any of the
early reservations overlap any others. When a Xen domain is built, it
constructs the initial address space as:
kernel text+data+bss
initrd
inital pagetable
Therefore, when reserving the pagetable (from &_end to
init_pg_tables_end), it covers the whole initrd area. If it then
tries to reserve the initrd, it will panic because of the overlap.
The simple fix here is to reserve INIT_PG_TABLE first, and then only
reserve the ramdisk if it doesn't overlap with the previous
reservations. A better/more complex fix might be to make
reserve_early() deal with overlapping reservations.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/kernel/head32.c | 6 ++++--
arch/x86/xen/enlighten.c | 2 +-
include/asm-x86/setup.h | 1 +
3 files changed, 6 insertions(+), 3 deletions(-)
===================================================================
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -66,6 +66,7 @@ void __init i386_start_kernel(void)
void __init i386_start_kernel(void)
{
reserve_early(__pa_symbol(&_text), __pa_symbol(&_end), "TEXT DATA BSS");
+ reserve_early(__pa_symbol(&_end), init_pg_tables_end, "INIT_PG_TABLE");
#ifdef CONFIG_BLK_DEV_INITRD
/* Reserve INITRD */
@@ -73,10 +74,11 @@ void __init i386_start_kernel(void)
u64 ramdisk_image = boot_params.hdr.ramdisk_image;
u64 ramdisk_size = boot_params.hdr.ramdisk_size;
u64 ramdisk_end = ramdisk_image + ramdisk_size;
- reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");
+ if (ramdisk_end < __pa_symbol(&_text) ||
+ ramdisk_image >= init_pg_tables_end)
+ reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");
}
#endif
- reserve_early(__pa_symbol(&_end), init_pg_tables_end, "INIT_PG_TABLE");
reserve_ebda_region();
===================================================================
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1264,5 +1264,5 @@ asmlinkage void __init xen_start_kernel(
}
/* Start the world */
- start_kernel();
+ i386_start_kernel();
}
===================================================================
--- a/include/asm-x86/setup.h
+++ b/include/asm-x86/setup.h
@@ -58,6 +58,7 @@ int __init copy_e820_map(struct e820entr
int __init copy_e820_map(struct e820entry *biosmap, int nr_map);
void __init add_memory_region(unsigned long long start,
unsigned long long size, int type);
+void __init i386_start_kernel(void);
extern unsigned long init_pg_tables_end;
--
