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Message-ID: <Pine.LNX.4.55.0808180510480.26857@cliff.in.clinika.pl>
Date: Mon, 18 Aug 2008 05:14:50 +0100 (BST)
From: "Maciej W. Rozycki" <macro@...ux-mips.org>
To: David Fries <david@...es.net>
cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Fix i486 suspend to disk CR4 oops
On Sun, 17 Aug 2008, David Fries wrote:
> arch/x86/power/cpu_32.c __save_processor_state calls read_cr4()
> only a i486 CPU doesn't have the CR4 register. Trying to read it
> produces an invalid opcode oops during suspend to disk.
[...]
> diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> index 81e5ab6..bd0f2a3 100644
> --- a/arch/x86/kernel/acpi/sleep.c
> +++ b/arch/x86/kernel/acpi/sleep.c
> @@ -86,7 +86,9 @@ int acpi_save_state_mem(void)
> #endif /* !CONFIG_64BIT */
>
> header->pmode_cr0 = read_cr0();
> - header->pmode_cr4 = read_cr4();
> + /* cr4 was introduced in the Pentium CPU */
> + if (boot_cpu_data.x86 >= 5)
> + header->pmode_cr4 = read_cr4();
> header->realmode_flags = acpi_realmode_flags;
> header->real_magic = 0x12345678;
>
NACK. Later i486 chips do have CR4 -- for PSE, VME, etc. (the set of
features varies across the line). Use a fixup as elsewhere or something.
Maciej
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