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List: kexec
Subject: [PATCH] x86: Introdudce a new option --force-vga
From: Kairui Song <kasong () redhat ! com>
Date: 2019-02-28 10:07:23
Message-ID: 20190228100723.13780-1-kasong () redhat ! com
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After commit 060eee58 "x86: use old screen_info if needed", kexec-tools
will force use old screen_info and vga type if failed to determine
current vga type. But it is not always a good idea.
Currently kernel hanging is inspected on some hyper-v VMs after this
commit, because hyperv_fb will mimic EFI (or VESA) VGA on first boot
up, but after the real driver is loaded, it will switch to new mode
and no longer compatible with EFI/VESA VGA. Keep setting
orig_video_isVGA to EFI/VESA VGA flag will get wrong driver loaded and
try to manipulate the framebuffer in a wrong way.
We can't ensure this won't happen on other framebuffer drivers, But
it's a helpful feature if the framebuffer drivers just work. So this
patch introduce a --force-vga options to let user decide if the
old screen_info should be used unconditional or not.
Signed-off-by: Kairui Song <kasong@redhat.com>
---
kexec/arch/i386/include/arch/options.h | 2 ++
kexec/arch/i386/kexec-x86.h | 1 +
kexec/arch/i386/x86-linux-setup.c | 7 +++++--
kexec/arch/x86_64/kexec-x86_64.c | 5 +++++
4 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/kexec/arch/i386/include/arch/options.h b/kexec/arch/i386/include/arch/options.h
index c113a83..7667cf4 100644
--- a/kexec/arch/i386/include/arch/options.h
+++ b/kexec/arch/i386/include/arch/options.h
@@ -32,6 +32,7 @@
#define OPT_ENTRY_32BIT (OPT_ARCH_MAX+10)
#define OPT_PASS_MEMMAP_CMDLINE (OPT_ARCH_MAX+11)
#define OPT_NOEFI (OPT_ARCH_MAX+12)
+#define OPT_FORCE_VGA (OPT_ARCH_MAX+13)
/* Options relevant to the architecture (excluding loader-specific ones): */
#define KEXEC_ARCH_OPTIONS \
@@ -45,6 +46,7 @@
{ "elf64-core-headers", 0, 0, OPT_ELF64_CORE }, \
{ "pass-memmap-cmdline", 0, 0, OPT_PASS_MEMMAP_CMDLINE }, \
{ "noefi", 0, 0, OPT_NOEFI}, \
+ { "force-vga", 0, 0, OPT_FORCE_VGA }, \
#define KEXEC_ARCH_OPT_STR KEXEC_OPT_STR ""
diff --git a/kexec/arch/i386/kexec-x86.h b/kexec/arch/i386/kexec-x86.h
index 51855f8..d16679f 100644
--- a/kexec/arch/i386/kexec-x86.h
+++ b/kexec/arch/i386/kexec-x86.h
@@ -52,6 +52,7 @@ struct arch_options_t {
enum coretype core_header_type;
uint8_t pass_memmap_cmdline;
uint8_t noefi;
+ uint8_t force_vga;
};
int multiboot_x86_probe(const char *buf, off_t len);
diff --git a/kexec/arch/i386/x86-linux-setup.c b/kexec/arch/i386/x86-linux-setup.c
index 1bd408b..0e92d26 100644
--- a/kexec/arch/i386/x86-linux-setup.c
+++ b/kexec/arch/i386/x86-linux-setup.c
@@ -144,7 +144,7 @@ static int setup_linux_vesafb(struct x86_linux_param_header *real_mode)
} else if (0 == strcmp(fix.id, "EFI VGA")) {
/* VIDEO_TYPE_EFI */
real_mode->orig_video_isVGA = 0x70;
- } else {
+ } else if (arch_options.force_vga) {
int err;
off_t offset = offsetof(typeof(*real_mode), orig_video_isVGA);
@@ -152,6 +152,9 @@ static int setup_linux_vesafb(struct x86_linux_param_header *real_mode)
err = get_bootparam(&real_mode->orig_video_isVGA, offset, 1);
if (err)
goto out;
+ } else {
+ real_mode->orig_video_isVGA = 0;
+ return 0;
}
close(fd);
@@ -844,7 +847,7 @@ void setup_linux_system_parameters(struct kexec_info *info,
setup_subarch(real_mode);
if (bzImage_support_efi_boot && !arch_options.noefi)
setup_efi_info(info, real_mode);
-
+
/* Default screen size */
real_mode->orig_x = 0;
real_mode->orig_y = 0;
diff --git a/kexec/arch/x86_64/kexec-x86_64.c b/kexec/arch/x86_64/kexec-x86_64.c
index 041b007..2e54381 100644
--- a/kexec/arch/x86_64/kexec-x86_64.c
+++ b/kexec/arch/x86_64/kexec-x86_64.c
@@ -55,6 +55,7 @@ void arch_usage(void)
" --console-serial Enable the serial console\n"
" --pass-memmap-cmdline Pass memory map via command line in kexec on panic case\n"
" --noefi Disable efi support\n"
+ " --force-vga Enabled vga blindly whenever possible \n"
);
}
@@ -67,6 +68,7 @@ struct arch_options_t arch_options = {
.core_header_type = CORE_TYPE_ELF64,
.pass_memmap_cmdline = 0,
.noefi = 0,
+ .force_vga = 0,
};
int arch_process_options(int argc, char **argv)
@@ -136,6 +138,9 @@ int arch_process_options(int argc, char **argv)
case OPT_NOEFI:
arch_options.noefi = 1;
break;
+ case OPT_FORCE_VGA:
+ arch_options.force_vga = 1;
+ break;
}
}
/* Reset getopt for the next pass; called in other source modules */
--
2.20.1
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