71 lines
2.6 KiB
Diff
71 lines
2.6 KiB
Diff
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# HG changeset patch
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# User Jan Beulich <jbeulich@suse.com>
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# Date 1347437974 -7200
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# Node ID 8c0aa97d529a55de2ab96be1a5a6e9ed6a9c6bf0
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# Parent ac8f4afccd6c6786a3fd5691e8b0c9b38c47e994
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x86-64/EFI: allow chaining of config files
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Namely when making use the CONFIG_XEN_COMPAT_* options in the legacy
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Linux kernels, newer kernels may not be compatible with older
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hypervisors, so trying to boot such a combination makes little sense.
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Booting older kernels on newer hypervisors, however, has to always
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work.
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With the way xen.efi looks for its configuration file, allowing
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individual configuration files to refer only to compatible kernels,
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and referring from an older- to a newer-hypervisor one (the kernels
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of which will, as said, necessarily be compatible with the older
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hypervisor) allows to greatly reduce redundancy at least in
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development environments where one frequently wants multiple
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hypervisors and kernles to be installed in parallel.
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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Acked-by: Keir Fraser <keir@xen.org>
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--- a/docs/misc/efi.markdown
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+++ b/docs/misc/efi.markdown
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@@ -75,6 +75,13 @@ Specifies an XSM module to load.
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Specifies a CPU microcode blob to load.
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+###`chain=<filename>`
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+
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+Specifies an alternate configuration file to use in case the specified section
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+(and in particular its `kernel=` setting) can't be found in the default (or
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+specified) configuration file. This is only meaningful in the [global] section
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+and really not meant to be used together with the `-cfg=` command line option.
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+
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Filenames must be specified relative to the location of the EFI binary.
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Extra options to be passed to Xen can also be specified on the command line,
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--- a/xen/arch/x86/efi/boot.c
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+++ b/xen/arch/x86/efi/boot.c
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@@ -797,7 +797,26 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SY
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else
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section.s = get_value(&cfg, "global", "default");
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- name.s = get_value(&cfg, section.s, "kernel");
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+ for ( ; ; )
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+ {
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+ name.s = get_value(&cfg, section.s, "kernel");
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+ if ( name.s )
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+ break;
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+ name.s = get_value(&cfg, "global", "chain");
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+ if ( !name.s )
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+ break;
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+ efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
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+ cfg.addr = 0;
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+ if ( !read_file(dir_handle, s2w(&name), &cfg) )
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+ {
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+ PrintStr(L"Chained configuration file '");
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+ PrintStr(name.w);
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+ efi_bs->FreePool(name.w);
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+ blexit(L"'not found\r\n");
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+ }
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+ pre_parse(&cfg);
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+ efi_bs->FreePool(name.w);
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+ }
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if ( !name.s )
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blexit(L"No Dom0 kernel image specified\r\n");
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split_value(name.s);
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