On 02/12/16 at 11:34pm, Baoquan He wrote: > Hi Lasse, > > I am checking a thread related to kaslr and setup_data issue on x86: > https://lkml.org/lkml/2015/7/7/963 > > Now I have a question about the commit from you: > > commit 303148045aac34b70db722a54e5ad94a3a6625c6 > Author: Lasse Collin <[email protected]> > Date: Wed Jan 12 17:01:24 2011 -0800 > > x86: support XZ-compressed kernel > > > In this commit for adding support of XZ-compressed kernel on x86, you > add extra 32K to the extract_offset. In commit log you said this is > because "The XZ decompressor needs around 30 KiB of heap, so the heap > size is increased to 32 KiB on both x86-32 and x86-64." With my > understanding decompression is done in decompression stage and it uses > boot_heap in arch/x86/boot/compressed/head_64.S, and boot_heap is > assigned to free_mem_ptr which is used for decompression heap malloc. > During this decompressio stage it's still in copied ZO space, why did > you add extra 32K space to extract_offset? If you want to increase the > decompression heap space shouldn't you decrease the extract_offset? Do I > misunderstand anything or miss things? > > Please help answer, I really don't understand this.
Lasse, please help have a look when it's convenient to you, many thanks. > > Thanks > Baoquan
