linux-kernel - Re: [PATCH] initramfs: Support initrd that is bigger then 2G.

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Message-ID: <53A3C177.1000905@zytor.com>
Date:	Thu, 19 Jun 2014 22:07:03 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	"Daniel M. Weeks" <dan@...weeks.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] initramfs: Support initrd that is bigger then 2G.

On 06/19/2014 10:02 PM, Yinghai Lu wrote:
> On Thu, Jun 19, 2014 at 9:29 PM, H. Peter Anvin <hpa@...or.com> wrote:
>> On 06/19/2014 07:12 PM, Yinghai Lu wrote:
>>>
>>> Also need to use that in write_buffer path for cpio that have file is
>>> more than file.
>>
>> That sentence doesn't make sense.
> 
> I mean this path:
>    unpack_to_rootfs  ===> write_buffer ===> actions[].../do_copy
> and image is uncompressed cpio, and there is one big file (>2G) in that cpio.

Don't tell me, make the description clear so someone can understand it
10 years from now.
>>
>> It would be nice in order to support very large initrd/initramfs, to
>> free the memory as it becomes available instead of requiring two copies
>> of the data in memory at the same time.
> 
> for initramfs, it is from ramdisk_image/ramdisk_size to tmpfs directly.
> and ramdisk_image/ramdisk_size get freed.
> 
> for initrd, it is transferred to /initrd.image in tmpfs at first, and
> ramdisk_image/ramdisk_size
> get freed,  at last /initrd.image is decompressed/copied to /dev/ram0
> and get removed
> from tempfs.
> 
> So what do you mean "free the memory"?
> 

For each of those transfers, we don't free the source memory until the
very end.  We could free that memory as we process the input, requiring
less total memory.

	-hpa


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