On 03/05/19 at 07:34pm, Kairui Song wrote:
> 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 --reuse-video-type options to let user decide if the
> old screen_info hould be used unconditional or not.
>
> Signed-off-by: Kairui Song <kasong@xxxxxxxxxx>
>
> ---
>
> Update from V1:
> - Fix a fd leak
> - Rename the option from --force-vga to --reuse-video-type
>
> kexec/arch/i386/include/arch/options.h | 2 ++
> kexec/arch/i386/kexec-x86.h | 1 +
> kexec/arch/i386/x86-linux-setup.c | 8 ++++++--
> kexec/arch/x86_64/kexec-x86_64.c | 5 +++++
> 4 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/kexec/arch/i386/include/arch/options.h b/kexec/arch/i386/include/arch/options.h
> index c113a83..0e57951 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_REUSE_VIDEO_TYPE (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}, \
> + { "reuse-video-type", 0, 0, OPT_REUSE_VIDEO_TYPE }, \
>
> #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..c2bcd37 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 reuse_video_type;
> };
>
> 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..8fad115 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.reuse_video_type) {
> int err;
> off_t offset = offsetof(typeof(*real_mode), orig_video_isVGA);
>
> @@ -152,6 +152,10 @@ 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;
> + close(fd);
> + return 0;
> }
> close(fd);
>
> @@ -844,7 +848,7 @@ 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..ccdc980 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"
> + " --reuse-video-type Reuse old boot time video type blindly\n"
> );
> }
>
> @@ -67,6 +68,7 @@ struct arch_options_t arch_options = {
> .core_header_type = CORE_TYPE_ELF64,
> .pass_memmap_cmdline = 0,
> .noefi = 0,
> + .reuse_video_type = 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_REUSE_VIDEO_TYPE:
> + arch_options.reuse_video_type = 1;
> + break;
> }
> }
> /* Reset getopt for the next pass; called in other source modules */
> --
> 2.20.1
>
Reviewed-by: Dave Young <dyoung@xxxxxxxxxx>
Thanks
Dave
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