From 5a17dae422d7de4b776a9753cd4673a343a25b4b Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Tue, 5 Aug 2014 11:52:11 +0100 Subject: efi: Add efi= parameter parsing to the EFI boot stub We need a way to customize the behaviour of the EFI boot stub, in particular, we need a way to disable the "chunking" workaround, used when reading files from the EFI System Partition. One of my machines doesn't cope well when reading files in 1MB chunks to a buffer above the 4GB mark - it appears that the "chunking" bug workaround triggers another firmware bug. This was only discovered with commit 4bf7111f5016 ("x86/efi: Support initrd loaded above 4G"), and that commit is perfectly valid. The symptom I observed was a corrupt initrd rather than any kind of crash. efi= is now used to specify EFI parameters in two very different execution environments, the EFI boot stub and during kernel boot. There is also a slight performance optimization by enabling efi=nochunk, but that's offset by the fact that you're more likely to run into firmware issues, at least on x86. This is the rationale behind leaving the workaround enabled by default. Also provide some documentation for EFI_READ_CHUNK_SIZE and why we're using the current value of 1MB. Tested-by: Ard Biesheuvel Cc: Roy Franz Cc: Maarten Lankhorst Cc: Leif Lindholm Cc: Borislav Petkov Signed-off-by: Matt Fleming --- Documentation/kernel-parameters.txt | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 5ae8608ca9f5..67d79597d9d6 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -992,10 +992,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Format: {"off" | "on" | "skip[mbr]"} efi= [EFI] - Format: { "old_map" } + Format: { "old_map", "nochunk" } old_map [X86-64]: switch to the old ioremap-based EFI runtime services mapping. 32-bit still uses this one by default. + nochunk: disable reading files in "chunks" in the EFI + boot stub, as chunking can cause problems with some + firmware implementations. efi_no_storage_paranoia [EFI; X86] Using this parameter you can use more than 50% of -- cgit v1.2.3 From b2e0a54a1296a91b800f316df7bef7d1905e4fd0 Mon Sep 17 00:00:00 2001 From: Dave Young Date: Thu, 14 Aug 2014 17:15:26 +0800 Subject: efi: Move noefi early param code out of x86 arch code noefi param can be used for arches other than X86 later, thus move it out of x86 platform code. Signed-off-by: Dave Young Signed-off-by: Matt Fleming --- Documentation/kernel-parameters.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 67d79597d9d6..08df275eee2b 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2169,7 +2169,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. nodsp [SH] Disable hardware DSP at boot time. - noefi [X86] Disable EFI runtime services support. + noefi Disable EFI runtime services support. noexec [IA-64] -- cgit v1.2.3 From 5ae3683c380e78aebc60d710617ba2c0dccc9e84 Mon Sep 17 00:00:00 2001 From: Dave Young Date: Thu, 14 Aug 2014 17:15:28 +0800 Subject: efi: Add kernel param efi=noruntime noefi kernel param means actually disabling efi runtime, Per suggestion from Leif Lindholm efi=noruntime should be better. But since noefi is already used in X86 thus just adding another param efi=noruntime for same purpose. Signed-off-by: Dave Young Signed-off-by: Matt Fleming --- Documentation/kernel-parameters.txt | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 08df275eee2b..d0e431611a04 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -992,13 +992,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Format: {"off" | "on" | "skip[mbr]"} efi= [EFI] - Format: { "old_map", "nochunk" } + Format: { "old_map", "nochunk", "noruntime" } old_map [X86-64]: switch to the old ioremap-based EFI runtime services mapping. 32-bit still uses this one by default. nochunk: disable reading files in "chunks" in the EFI boot stub, as chunking can cause problems with some firmware implementations. + noruntime : disable EFI runtime services support efi_no_storage_paranoia [EFI; X86] Using this parameter you can use more than 50% of -- cgit v1.2.3