Messages in this thread | | | Date | Thu, 8 Oct 2020 11:48:36 +0200 | From | Joerg Roedel <> | Subject | Re: [PATCH 4/5] x86/boot/64: Explicitly map boot_params and command line |
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On Wed, Oct 07, 2020 at 03:53:50PM -0400, Arvind Sankar wrote: > This is fragile, as boot_params and the command line mappings are > required for the main kernel. If EARLY_PRINTK and RANDOMIZE_BASE are > disabled, a QEMU/OVMF boot never accesses the command line in the > decompressor stub, and so it never gets mapped. The main kernel accesses > it from the identity mapping if AMD_MEM_ENCRYPT is enabled, and will > crash.
Looked again, and I think that is wrong for boot_params, which are touched unconditionally at the beginning of extract_kernel().
For the cmdline you are right, but one of CONFIG_ACPI, CONFIG_RANDOMIZE_BASE, CONFIG_X86_5LEVEL or CONFIG_EARLY_PRINTK is sufficient to have it touched during this boot stage.
Regards,
Joerg
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