On Thu, Apr 4, 2013 at 1:11 AM, HATAYAMA Daisuke
<d.hatay...@jp.fujitsu.com> wrote:
> (2013/04/04 9:38), Yinghai Lu wrote:
>
>> Index: linux-2.6/lib/swiotlb.c
>> ===================================================================
>> --- linux-2.6.orig/lib/swiotlb.c
>> +++ linux-2.6/lib/swiotlb.c
>> @@ -105,9 +105,9 @@ setup_io_tlb_npages(char *str)
>> if (!strcmp(str, "force"))
>> swiotlb_force = 1;
>>
>> - return 1;
>> + return 0;
>> }
>> -__setup("swiotlb=", setup_io_tlb_npages);
>> +early_param("swiotlb", setup_io_tlb_npages);
>> /* make io_tlb_overflow tunable too? */
>>
>> unsigned long swiotlb_nr_tbl(void)
>> @@ -115,6 +115,18 @@ unsigned long swiotlb_nr_tbl(void)
>> return io_tlb_nslabs;
>> }
>> EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);
>> +
>> +/* default to 64MB */
>> +#define IO_TLB_DEFAULT_SIZE (64UL<<20)
>> +unsigned long swiotlb_size_or_default(void)
>> +{
>> + unsigned long size;
>> +
>> + size = io_tlb_nslabs << IO_TLB_SHIFT;
>> +
>> + return size ? size : (IO_TLB_DEFAULT_SIZE);
>> +}
>> +
>> /* Note that this doesn't work with highmem page */
>> static dma_addr_t swiotlb_virt_to_bus(struct device *hwdev,
>> volatile void *address)
>> @@ -188,8 +200,7 @@ int __init swiotlb_init_with_tbl(char *t
>> void __init
>> swiotlb_init(int verbose)
>> {
>> - /* default to 64MB */
>> - size_t default_size = 64UL<<20;
>> + size_t default_size = IO_TLB_DEFAULT_SIZE;
>> unsigned char *vstart;
>> unsigned long bytes;
>
> The variable default_size seems no longer necessary. IO_TLB_DEFAULT_SIZE
> should be used directly.
Yes, but that does not hurt.
>
>>
>> Index: linux-2.6/Documentation/kernel-parameters.txt
>> ===================================================================
>> --- linux-2.6.orig/Documentation/kernel-parameters.txt
>> +++ linux-2.6/Documentation/kernel-parameters.txt
>> @@ -596,9 +596,6 @@ bytes respectively. Such letter suffixes
>> is selected automatically. Check
>> Documentation/kdump/kdump.txt for further details.
>>
>> - crashkernel_low=size[KMG]
>> - [KNL, x86] parts under 4G.
>> -
>> crashkernel=range1:size1[,range2:size2,...][@offset]
>> [KNL] Same as above, but depends on the memory
>> in the running system. The syntax of range is
>> @@ -606,6 +603,18 @@ bytes respectively. Such letter suffixes
>> a memory unit (amount[KMG]). See also
>> Documentation/kdump/kdump.txt for an example.
>>
>> + crashkernel_low=size[KMG]
>> + [KNL, x86_64] range under 4G. When crashkernel= is
>> + passed, kernel allocate physical memory region
>> + above 4G, that cause second kernel crash on system
>> + that need swiotlb later. Kernel would try to allocate
>> + some region below 4G automatically. This one let
>> + user to specify own low range under 4G for second
>> + kernel instead.
>
> In fact, swiotlb caused the 2nd kernel to fail to boot this time, but in
> general, other components that require low memory can cause the same
> situation. I think it better to avoid the description that only swiotlb
> can cause the 2nd kernel to fail to boot.
>
> So, how about this?
>
> ... that cause second kernel crash on system that require some amount of
> low memory, e.g. swiotlb that requires at least 72MB low memory at
> default. Kernel would ...
ok, will change that.
>
>> + 0: to disable low allocation on systems that do not
>> + need swiotlb, that will save 72M low ram in first
>> + kernel.
>> +
>
> Similarly, I think it better not to say swiotlb thing here. Just:
>
> 0: to disable automatic low memory allocation.
ok,
it will be:
---
crashkernel_low=size[KMG]
[KNL, x86_64] range under 4G. When crashkernel= is
passed, kernel allocate physical memory region
above 4G, that cause second kernel crash on system
that require some amount of low memory, e.g. swiotlb
requires at least 64M+32K low memory. Kernel would
try to allocate 72M below 4G automatically.
This one let user to specify own low range under 4G
for second kernel instead.
0: to disable low allocation.
---
Thanks
Yinghai
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