[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2 0/6] Clean up x86_64 boot code
Some cleanups for the boot path, originally inspired by an attempt to avoid scribbling on arbitrarily-chosen low memory. In the no-real-mode case we don't need to bounce through low memory at all; we can run the 32-bit trampoline in-place in the Xen image. The variables containing information which is optionally discovered by the real-mode boot code can be put back in place in the Xen image and we can dispense with the bootsym() pointer gymnastics in C code which access them in low memory. I haven't yet got to reloc(), which I think exists only to ensure that the various breadcrumbs left all over the place by the Multiboot bootloader aren't scribbled on when we copy the 16-bit boot trampoline into low memory. I'd quite like to kill reloc() and pass the original pointer up to 64-bit code to be handled in C. That would require finding a *safe* location to put the 16-bit boot trampoline though, which doesn't already contain anything that the bootloader created for us. In fact, isn't there already a chance that head.S will choose a location for the trampoline which is already part of a module or contains one of the Multiboot breadcrumbs? https://xenbits.xen.org/gitweb/?p=people/dwmw2/xen.git;a=shortlog;h=refs/heads/bootcleanup v2: Patch #1 is the first series is already merged. Fold in minor fixup from Andrew to what is now patch #1. Verbally agree to overcome Jan's objections to patch #1, in Chicago. David Woodhouse (6): x86/boot: Remove gratuitous call back into low-memory code x86/boot: Only jump into low trampoline code for real-mode boot x86/boot: Split bootsym() into four types of relocations x86/boot: Rename trampoline_{start,end} to boot_trampoline_{start,end} x86/boot: Copy 16-bit boot variables back up to Xen image x86/boot: Do not use trampoline for no-real-mode boot paths xen/arch/x86/acpi/power.c | 6 +- xen/arch/x86/boot/edd.S | 18 ++-- xen/arch/x86/boot/head.S | 89 +++++++++++++----- xen/arch/x86/boot/mem.S | 35 ++----- xen/arch/x86/boot/trampoline.S | 146 ++++++++++++++++++++++++------ xen/arch/x86/boot/video.S | 36 ++++---- xen/arch/x86/boot/wakeup.S | 12 +-- xen/arch/x86/cpu/common.c | 2 +- xen/arch/x86/cpu/intel.c | 2 +- xen/arch/x86/efi/efi-boot.h | 31 +------ xen/arch/x86/platform_hypercall.c | 18 ++-- xen/arch/x86/setup.c | 71 ++++++++++++--- xen/arch/x86/smpboot.c | 6 +- xen/arch/x86/tboot.c | 6 +- xen/arch/x86/x86_64/mm.c | 2 +- xen/arch/x86/xen.lds.S | 27 ++++-- xen/include/asm-x86/acpi.h | 2 +- xen/include/asm-x86/config.h | 10 +- xen/include/asm-x86/e820.h | 5 +- xen/include/asm-x86/edd.h | 1 - 20 files changed, 336 insertions(+), 189 deletions(-) Attachment:
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