Re: [PATCH v7u1 26/31] x86: Don't enable swiotlb if there is notenough ram for it

[Yinghai Lu]

On Fri, Jan 4, 2013 at 2:26 PM, Shuah Khan <shuahkhan@xxxxxxxxx> wrote:

> However, I think regression on existing behavior with a
> panic is a bit of a big hammer. Thie change causes panic on systems
> even when kdump is not enabled, if I understand it correctly.

I don't think so.

+static bool __init enough_mem_for_swiotlb(void)
+{
+       /* do we have less than 1M RAM under 4G ? */
+       return memblock_mem_size(1ULL<<(32-PAGE_SHIFT)) > (1ULL<<20);
+}

enough_mem_for_swiotlb could return false for them?

and

 int __init pci_swiotlb_detect_override(void)
 {
-       int use_swiotlb = swiotlb | swiotlb_force;
-
        if (swiotlb_force)
                swiotlb = 1;
+       else if (!enough_mem_for_swiotlb())
+               swiotlb = 0;

-       return use_swiotlb;
+       return swiotlb;
 }

it only disable swiotlb when there is less 1M mem under 4G.
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