From: Joerg Roedel <[email protected]> When the crash kernel is loaded above 4GiB in memory, the first kernel allocates only 72MiB of low-memory for the DMA requirements of the second kernel. On systems with many devices this is not enough and causes device driver initialization errors and failed crash dumps. Testing by SUSE and Redhat has shown that 256MiB is a good default value for now and the discussion has lead to this value as well. So set this default value to 256MiB to make sure there is enough memory available for DMA.
Signed-off-by: Joerg Roedel <[email protected]> Acked-by: Baoquan He <[email protected]> Cc: Baoquan He <[email protected]> Cc: Dave Young <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Jörg Rödel <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Vivek Goyal <[email protected]> Cc: [email protected] Cc: x86-ml <[email protected]> Link: http://lkml.kernel.org/r/[email protected] [ Reflow comment. ] Signed-off-by: Borislav Petkov <[email protected]> --- arch/x86/kernel/setup.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index d74ac33290ae..5a697e56634c 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -531,12 +531,15 @@ static void __init reserve_crashkernel_low(void) if (ret != 0) { /* * two parts from lib/swiotlb.c: - * swiotlb size: user specified with swiotlb= or default. - * swiotlb overflow buffer: now is hardcoded to 32k. - * We round it to 8M for other buffers that - * may need to stay low too. + * - swiotlb size: user-specified with swiotlb= or default. + * + * -swiotlb overflow buffer: now hardcoded to 32k. + * + * We round it to 8M for other buffers that may need to stay low + * too. Also make sure we allocate enough extra low memory so + * that we don't run out of DMA buffers for 32-bit devices. */ - low_size = swiotlb_size_or_default() + (8UL<<20); + low_size = max(swiotlb_size_or_default() + (8UL<<20), 256UL<<20); auto_set = true; } else { /* passed with crashkernel=0,low ? */ -- 2.3.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
