On Friday, November 04, 2011, Barry Song wrote:
> From: Barry Song <Baohua.Song@xxxxxxx>
>
> Current swsusp requires swap partitions even larger than real saved pages
> due to the worst compress ratio:
> but for an embedded system, which has limited storage space, then it might
> can't give the big size partition to save snapshot.
> In the another way, some embedded systems can definitely know the most size
> needed for snapshot since they run some specific application lists.
> So this patch provides the possibility for bootloader to tell kernel even
> the system has a little snapshot partition, but it is still enough.
> For example, if the system need to save 120MB memory, origin swsusp will require
> a 130MB partition to save snapshot. but if users know 30MB is enough for them(
> compressed image will be less than 30MB), they just make a 30MB partition.
>
> Signed-off-by: Barry Song <Baohua.Song@xxxxxxx>
> Cc: Xiangzhen Ye <Xiangzhen.Ye@xxxxxxx>
I'm considering this as 3.3 material, so I'll take care of it after the current
merge window closes.
Thanks,
Rafael
> ---
> this is another patch after I provide resumewait/resumedelay kernel params
> to make swsusp support embedded systems better.
> This patch is tested on CSR SiRFprimaII platform.
>
> Documentation/kernel-parameters.txt | 7 +++++++
> kernel/power/swap.c | 13 +++++++++++++
> 2 files changed, 20 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index a0c5c5f..2ad2e9c 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -2277,6 +2277,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
> in <PAGE_SIZE> units (needed only for swap files).
> See Documentation/power/swsusp-and-swap-files.txt
>
> + swapenough [SWSUSP]
> + Tell kernel the swap partition size is enough and let kernel
> + skip checking whether the swap partition has enough size to
> + save snapshot.
> + It is used for embedded systems, typically using NAND and SD
> + card, which have not large space.
> +
> resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
> read the resume files
>
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index 11a594c..97c30b5 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -36,6 +36,8 @@
>
> #define HIBERNATE_SIG "S1SUSPEND"
>
> +static int swapenough;
> +
> /*
> * The swap map is a data structure used for keeping track of each page
> * written to a swap partition. It consists of many swap_map_page
> @@ -772,6 +774,9 @@ static int enough_swap(unsigned int nr_pages, unsigned int flags)
> unsigned int free_swap = count_swap_pages(root_swap, 1);
> unsigned int required;
>
> + if (swapenough)
> + return 1;
> +
> pr_debug("PM: Free swap pages: %u\n", free_swap);
>
> required = PAGES_FOR_IO + ((flags & SF_NOCOMPRESS_MODE) ?
> @@ -1449,3 +1454,11 @@ static int swsusp_header_init(void)
> }
>
> core_initcall(swsusp_header_init);
> +
> +static int __init swapenough_setup(char *str)
> +{
> + swapenough = 1;
> + return 1;
> +}
> +
> +__setup("swapenough", swapenough_setup);
>
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