From 6f44d0337cc54a46e83b4c8a6195607e78fff71d Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Fri, 27 Aug 2010 14:19:33 -0400 Subject: x86, doc: Adding comments about .iommu_table and its neighbors. Updating the linker section with comments about .iommu_table and some other ones that I know of. CC: Sam Ravnborg CC: H. Peter Anvin CC: Fujita Tomonori CC: Thomas Gleixner CC: Ingo Molnar Signed-off-by: Konrad Rzeszutek Wilk LKML-Reference: <1282933173-19960-1-git-send-email-konrad.wilk@oracle.com> Signed-off-by: H. Peter Anvin --- arch/x86/kernel/vmlinux.lds.S | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'arch/x86/kernel/vmlinux.lds.S') diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index b92e040..3f07c37 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -242,6 +242,12 @@ SECTIONS __x86_cpu_dev_end = .; } + /* + * start address and size of operations which during runtime + * can be patched with virtualization friendly instructions or + * baremetal native ones. Think page table operations. + * Details in paravirt_types.h + */ . = ALIGN(8); .parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) { __parainstructions = .; @@ -249,6 +255,11 @@ SECTIONS __parainstructions_end = .; } + /* + * struct alt_inst entries. From the header (alternative.h): + * "Alternative instructions for different CPU types or capabilities" + * Think locking instructions on spinlocks. + */ . = ALIGN(8); .altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) { __alt_instructions = .; @@ -256,10 +267,21 @@ SECTIONS __alt_instructions_end = .; } + /* + * And here are the replacement instructions. The linker sticks + * them as binary blobs. The .altinstructions has enough data to + * get the address and the length of them to patch the kernel safely. + */ .altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) { *(.altinstr_replacement) } + /* + * struct iommu_table_entry entries are injected in this section. + * It is an array of IOMMUs which during run time gets sorted depending + * on its dependency order. After rootfs_initcall is complete + * this section can be safely removed. + */ .iommu_table : AT(ADDR(.iommu_table) - LOAD_OFFSET) { __iommu_table = .; *(.iommu_table) -- cgit v1.1