Re: [RFC PATCH] x86: make sure wakeup code is below 1M

From: Rafael J. Wysocki
Date: Mon Nov 09 2009 - 07:13:51 EST


On Monday 09 November 2009, Yinghai Lu wrote:
>
> try to find_e820_area/reserve_early, and call acpi_reserve_memory early
>
> to get area is below 1M
>
> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>

I generally like it, two comments below.

> ---
> arch/x86/include/asm/acpi.h | 2 +-
> arch/x86/kernel/acpi/sleep.c | 15 +++++++++------
> arch/x86/kernel/setup.c | 13 +++++++------
> 3 files changed, 17 insertions(+), 13 deletions(-)
>
> Index: linux-2.6/arch/x86/include/asm/acpi.h
> ===================================================================
> --- linux-2.6.orig/arch/x86/include/asm/acpi.h
> +++ linux-2.6/arch/x86/include/asm/acpi.h
> @@ -118,7 +118,7 @@ extern void acpi_restore_state_mem(void)
> extern unsigned long acpi_wakeup_address;
>
> /* early initialization routine */
> -extern void acpi_reserve_bootmem(void);
> +extern void acpi_reserve_memory(void);

If you change the name of the function, IMO it would be better to call it
something like acpi_reserve_wakeup_memory(). This way it would be clear what
the memory is reserved for.

> /*
> * Check if the CPU can handle C2 and deeper
> Index: linux-2.6/arch/x86/kernel/acpi/sleep.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/acpi/sleep.c
> +++ linux-2.6/arch/x86/kernel/acpi/sleep.c
> @@ -119,29 +119,32 @@ void acpi_restore_state_mem(void)
>
>
> /**
> - * acpi_reserve_bootmem - do _very_ early ACPI initialisation
> + * acpi_reserve_memory - do _very_ early ACPI initialisation
> *
> * We allocate a page from the first 1MB of memory for the wakeup
> * routine for when we come back from a sleep state. The
> * runtime allocator allows specification of <16MB pages, but not
> * <1MB pages.
> */
> -void __init acpi_reserve_bootmem(void)
> +void __init acpi_reserve_memory(void)
> {
> + unsigned long mem;
> +
> if ((&wakeup_code_end - &wakeup_code_start) > WAKEUP_SIZE) {
> printk(KERN_ERR
> "ACPI: Wakeup code way too big, S3 disabled.\n");
> return;
> }
>
> - acpi_realmode = (unsigned long)alloc_bootmem_low(WAKEUP_SIZE);
> + mem = find_e820_area(0, 1<<20, WAKEUP_SIZE, PAGE_SIZE);
>
> - if (!acpi_realmode) {
> + if (mem == -1L) {

Could we change the condition to avoid the "-1L" here? It doesn't look very
nice.

> printk(KERN_ERR "ACPI: Cannot allocate lowmem, S3 disabled.\n");
> return;
> }
> -
> - acpi_wakeup_address = virt_to_phys((void *)acpi_realmode);
> + acpi_realmode = (unsigned long) phys_to_virt(mem);
> + acpi_wakeup_address = mem;
> + reserve_early(mem, mem + WAKEUP_SIZE, "WAKEUP");
> }

Thanks,
Rafael
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