Bug#1069844: More debug info
Alex Bennée
alex.bennee at linaro.org
Thu Apr 25 20:32:18 BST 2024
Julian Andres Klode <julian.klode at canonical.com> writes:
> On Thu, Apr 25, 2024 at 06:30:52PM +0100, Alex Bennée wrote:
>>
>> Continuing to debug on QEMU it seems there is an incompatibility with
>> the images and the peloader (which overrides the normal efi loader):
>>
>> Thread 1 hit Breakpoint 3.2, grub_load_normal_mode () at ../../../grub-core/kern/main.c:241
>> 241 in ../../../grub-core/kern/main.c
>> (grub gdb) hbreak do_load_image
>> Hardware assisted breakpoint 4 at 0x23bdf0e00: do_load_image. (2 locations)
>> (grub gdb) c
>> Continuing.
>> add symbol table from file "bli.module" at
>> .text_addr = 0x23ba772e0
>> .bss_addr = 0x0
>> .module_license_addr = 0x23ba7764a
>> .data_addr = 0x0
>> .rodata.str1.1_addr = 0x23ba77560
>> .rodata_addr = 0x23ba77550
>> add symbol table from file "xen_boot.module" at
>> .text_addr = 0x23bcef3c0
>> .bss_addr = 0x23bcf0370
>> .module_license_addr = 0x23bcf035e
>> .data_addr = 0x0
>> .rodata.str1.1_addr = 0x23bcefff8
>>
>> Thread 1 hit Breakpoint 4.1, do_load_image (boot_policy=0 '\000', parent_image_handle=0x23e889f18, file_path=0x237d1bce0, source_buffer=0x239f00000, source_size=1081352,
>> image_handle=0x4766c498) at ../../../grub-core/loader/efi/peimage.c:745
>> warning: 745 ../../../grub-core/loader/efi/peimage.c: No such file or directory
>> (grub gdb) hbreak grub_error
>> Hardware assisted breakpoint 5 at 0x6db0: grub_error. (2 locations)
>> (grub gdb) c
>> Continuing.
>>
>> Thread 1 hit Breakpoint 4.2, 0x000000023bdf0e4c in do_load_image (boot_policy=<optimized out>, parent_image_handle=<optimized out>, image_handle=<optimized out>,
>> source_size=<optimized out>, source_buffer=<optimized out>, file_path=<optimized out>) at ../../../grub-core/loader/efi/peimage.c:751
>> 751 in ../../../grub-core/loader/efi/peimage.c
>> (grub gdb) c
>> Continuing.
>>
>> Thread 1 hit Breakpoint 5.2, grub_error (n=GRUB_ERR_BAD_OS, fmt=0x23bdf1703 "section inside header") at ../../../grub-core/kern/err.c:41
>> warning: 41 ../../../grub-core/kern/err.c: No such file or directory
>> (grub gdb) bt
>> #0 grub_error (n=GRUB_ERR_BAD_OS, fmt=0x23bdf1703 "section inside header") at ../../../grub-core/kern/err.c:41
>> #1 0x000000023bdf0e34 in do_load_image (boot_policy=<optimized out>, parent_image_handle=<optimized out>, file_path=<optimized out>, source_buffer=<optimized out>,
>> source_size=<optimized out>, image_handle=<optimized out>) at ../../../grub-core/loader/efi/peimage.c:747
>> #2 0x000000023bedabdc in grub_arch_efi_linux_boot_image (addr=9561964544, size=1081352,
>> args=0x23bbb8b00 "placeholder dom0_mem=4G,max:4G loglvl=all guest_loglvl=all no-real-mode edd=off") at ../../../grub-core/loader/efi/linux.c:210
>> #3 0x000000023bff41bc in grub_loader_boot () at ../../../grub-core/commands/boot.c:211
>> #4 grub_loader_boot () at ../../../grub-core/commands/boot.c:190
>> #5 0x000000023bf42158 in grub_command_execute (name=0x23bf4e72c "boot", argc=0, argv=0x0 <_start>) at ../../../include/grub/command.h:126
>> #6 grub_menu_execute_entry (entry=entry at entry=0x23bd17660, auto_boot=auto_boot at entry=0) at ../../../grub-core/normal/menu.c:306
>> #7 0x000000023bf41e2c in show_menu (autobooted=<optimized out>, nested=<optimized out>, menu=<optimized out>) at ../../../grub-core/normal/menu.c:925
>> #8 grub_show_menu (menu=menu at entry=0x23bd1a940, nested=nested at entry=1, autoboot=autoboot at entry=0) at ../../../grub-core/normal/menu.c:940
>> #9 0x000000023bf408a8 in grub_normal_execute (config=<optimized out>, nested=nested at entry=1, batch=batch at entry=0) at ../../../grub-core/normal/main.c:291
>> #10 0x000000023bf32260 in grub_cmd_source (cmd=<optimized out>, argc=1, args=0x23bd1fcc8) at ../../../grub-core/commands/configfile.c:48
>> #11 grub_cmd_source (cmd=<optimized out>, argc=<optimized out>, args=0x23bd1fcc8) at ../../../grub-core/commands/configfile.c:30
>> #12 0x000000023bf48d0c in grub_script_execute_cmdline (cmd=<optimized out>) at ../../../grub-core/script/execute.c:1034
>> #13 0x000000023bf478c0 in grub_script_execute_cmd (cmd=cmd at entry=0x23bd190c8) at ../../../grub-core/script/execute.c:819
>> #14 0x000000023bf4874c in grub_script_execute_cmdlist (list=<optimized out>) at ../../../grub-core/script/execute.c:1079
>> #15 0x000000023bf478c0 in grub_script_execute_cmd (cmd=<optimized out>) at ../../../grub-core/script/execute.c:819
>> #16 0x000000023bf489b4 in grub_script_execute (script=<optimized out>) at ../../../grub-core/script/execute.c:1191
>> #17 0x000000023bf497fc in grub_normal_parse_line (line=line at entry=0x23bd20060 "configfile $prefix/grub.cfg", getline=getline at entry=0x23bf40430 <read_config_file_getline>,
>> getline_data=getline_data at entry=0x23bd20380) at ../../../grub-core/script/main.c:36
>> #18 0x000000023bf409a0 in read_config_file (config=0x23bd20780 "(hd0,gpt1)/EFI/debian/grub.cfg") at ../../../grub-core/normal/main.c:179
>> #19 grub_normal_execute (config=config at entry=0x23bd20780 "(hd0,gpt1)/EFI/debian/grub.cfg", nested=nested at entry=0, batch=batch at entry=0)
>> at ../../../grub-core/normal/main.c:277
>> #20 0x000000023bf40ca4 in grub_enter_normal_mode (config=config at entry=0x23bd20780 "(hd0,gpt1)/EFI/debian/grub.cfg") at ../../../grub-core/normal/main.c:304
>> #21 0x000000023bf40da0 in grub_try_normal_prefix (prefix=0x23bd209a0 "(hd0,gpt1)/EFI/debian") at ../../../grub-core/normal/main.c:356
>> #22 0x000000023bf40ea0 in grub_try_normal (variable=0x23bf4e492 "fw_path") at ../../../grub-core/normal/main.c:407
>> #23 grub_cmd_normal (cmd=<optimized out>, argc=0, argv=<optimized out>) at ../../../grub-core/normal/main.c:421
>> #24 grub_cmd_normal (cmd=<optimized out>, argc=<optimized out>, argv=<optimized out>) at ../../../grub-core/normal/main.c:412
>> #25 0x000000023c018fb8 in grub_command_execute (name=0x23c01ec6e ")", argc=0, argv=0x0 <_start>) at ../../../include/grub/command.h:126
>> #26 grub_load_normal_mode () at ../../../grub-core/kern/main.c:247
>> #27 grub_main () at ../../../grub-core/kern/main.c:339
>> #28 0x000000023c5c02c8 in ?? ()
>> #29 0x000000023c62a000 in ?? ()
>> #30 0xafafafaf6c617470 in ?? ()
>> Backtrace stopped: previous frame identical to this frame (corrupt stack?)
>>
>> Is it possible to override the peloader or does the Xen image need to be
>> prepared a certain way?
>
> Well it needs to be a proper UEFI binary. The loader works for Linux
> and for chainloading the Windows boot loader, we haven't tested other
> binaries (except some small test binaries I suppose).
I'm able to load the hypervisor directly (it appears as a Linux kernel
ARM64 boot executable Image, little-endian, 4K pages). Also using the
upstream grub its able to load the hypervisor with the direct EFI
load_image boot service.
> Personally, I'm surprised Xen still exists in 2024, so don't expect
> me to be very helpful here.
There are still use cases for a "traditional" lowvisor type hypervisor
that isn't entangled with a whole kernel. In our case there are
automotive use cases which benefit from Xen's ability to partition and
pin vCPUs to different domains.
I don't know what Debian's policy is towards Xen but it did at least use
to work.
> In the error case you can see though, that one of the section
> addresses in the Xen binary to be relocated points into the (PE)
> header of the binary, which obviously seems wrong.
>
> So go check your PE sections and check which one is wrong?
Is there any tooling for examining PE sections?
--
Alex Bennée
Virtualisation Tech Lead @ Linaro
More information about the Pkg-grub-devel
mailing list