Re: [PATCH] x86: let 'reservetop' functioning right

From: Liang Li
Date: Tue Mar 30 2010 - 22:53:47 EST


Hi Ingo,

Seems the problem still there in 2.6.34-rc3. When pass
'reservetop=0x1000' to x86_32 kernel, kernel hangs on
very early boot stage.

Do we have any plan to abandon 'reservetop' or due to
some reason that the patch is non-acceptable?

Thanks,
-Liang Li

On Thu, Mar 25, 2010 at 08:54:05AM +0800, Liang Li wrote:
> When specify 'reservetop=0xabc000' kernel parameter, kernel will hang
> on boot due to a early_ioremap bug that relate to commit 8827247ff.
>
> The root cause of boot failure problem is the value of 'slot_virt[i]'
> was initialized in setup_arch->early_ioremap_init. But later in
> setup_arch, the function 'parse_early_param' will modify 'FIXADDR_TOP'
> when 'reservetop=0xbadc0de' being specified.
>
> The simplest fix might be use __fix_to_virt(idx0) to get updated value
> of 'FIXADDR_TOP' in '__early_ioremap' instead of reference old value
> from slot_virt[slot] directly.
>
> Signed-off-by: Liang Li <liang.li@xxxxxxxxxxxxx>
> ---
> arch/x86/mm/ioremap.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index 5eb1ba7..ea82ef0 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -537,9 +537,9 @@ __early_ioremap(resource_size_t phys_addr, unsigned long size, pgprot_t prot)
> --nrpages;
> }
> if (early_ioremap_debug)
> - printk(KERN_CONT "%08lx + %08lx\n", offset, slot_virt[slot]);
> + printk(KERN_CONT "%08lx + %08lx\n", offset, __fix_to_virt(idx0));
>
> - prev_map[slot] = (void __iomem *)(offset + slot_virt[slot]);
> + prev_map[slot] = (void __iomem *)(offset + __fix_to_virt(idx0));
> return prev_map[slot];
> }
>
> --
> 1.6.6
>
> --
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