[PATCH v4 2/5] efi: Show the location of the bounce buffer when debugging

[Simon Glass]

Hi Heinrich,

On Fri, 11 Oct 2024 at 16:02, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
>
>
> Am 11. Oktober 2024 23:21:23 MESZ schrieb Simon Glass <sjg at chromium.org>:
> >The EFI_LOADER_BOUNCE_BUFFER feature was added many years ago. It is
> >still needed and 24 boards (lx2160ardb_tfa_stmm,
> >lx2162aqds_tfa_SECURE_BOOT and the like) use it.
> >
> >This feature uses EFI page allocation to create a 64MB buffer 'in space'
> >without any knowledge of where boards intend to load their images. This
> >may result in image corruption or other problems.
> >
> >For example, if the feature is enabled on qemu_arm64 it puts the EFI
> >bounce buffer at 1045MB, with the kernel at 1028MB and the ramdisk at
> >1088MB. The kernel is probably smaller than 27MB but the buffer does
> >overlap the ramdisk.
> >
> >The solution is probably to use BOUNCE_BUFFER instead, with the EFI
> >version being dropped. For now, show the address of the EFI bounce
> >buffer so people have a better chance to debug any problem.
> >
> >Signed-off-by: Simon Glass <sjg at chromium.org>
> >---
> >In response to questions on how to show this problem:
> >
> >First, add CONFIG_EFI_LOADER_BOUNCE_BUFFER=y to
> >configs/qemu_arm64_defconfig and build
> >
> >Then, to run:
> >qemu-system-aarch64 -machine virt -nographic -cpu cortex-a57 \
> >   -bios u-boot.bin
> >
> >U-Boot 2024.10-00809-gae29e5f76e4a-dirty (Oct 11 2024 - 11:48:46 -0600)
> >
> >DRAM:  128 MiB
> >Core:  51 devices, 14 uclasses, devicetree: board
> >Flash: 64 MiB
> >Loading Environment from Flash... *** Warning - bad CRC, using default environment
> >
> >In:    serial,usbkbd
> >Out:   serial,vidconsole
> >Err:   serial,vidconsole
> >No USB controllers found
> >Net:   eth0: virtio-net#32
> >
> >starting USB...
> >No USB controllers found
> >Hit any key to stop autoboot:  0
> >=> bootefi hello
> >Enabling coop memory
> >No EFI system partition
> >No EFI system partition
> >Failed to persist EFI variables
> >Missing TPMv2 device for EFI_TCG_PROTOCOL
> >Missing RNG device for EFI_RNG_PROTOCOL
> >Warning: EFI bounce buffer 000000004157f000-000000004557f000
> >Not loaded from disk
> >Booting /MemoryMapped(0x0,0x47763730,0x31b0)
> >EFI: Call: efi_load_image(false, efi_root, file_path, source_buffer, source_size, &handle)
> >EFI: 0 returned by efi_load_image(false, efi_root, file_path, source_buffer, source_size, &handle)
> >Hello, world!
> >Running on UEFI 2.10
> >Firmware vendor: Das U-Boot
> >Firmware revision: 20241000
> >Have device tree
> >Load options: <none>
> >File path: <none>
> >Boot device: /MemoryMapped(0x0,0x47763730,0x31b0)
> >=> print kernel_addr_r
> >kernel_addr_r=0x40400000
> >=> print ramdisk_addr_r
> >ramdisk_addr_r=0x44000000
> >=>
> >
> >The EFI bounce buffer overlaps with the ramdisk.
> >
> >Changes in v4:
> >- Reword the commit message since this feature is needed
> >
> > lib/efi_loader/efi_bootbin.c | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> >diff --git a/lib/efi_loader/efi_bootbin.c b/lib/efi_loader/efi_bootbin.c
> >index a87006b3c0e..eefdd660cee 100644
> >--- a/lib/efi_loader/efi_bootbin.c
> >+++ b/lib/efi_loader/efi_bootbin.c
> >@@ -209,6 +209,15 @@ efi_status_t efi_binary_run(void *image, size_t size, void *fdt)
> >               return -1;
> >       }
> >
> >+#ifdef CONFIG_EFI_LOADER_BOUNCE_BUFFER
> >+      /*
> >+       * Add a warning about this buffer, since it may conflict with other
> >+       * things
> >+       */
> >+      log_debug("Warning: EFI bounce buffer %p-%p\n", efi_bounce_buffer,
> >+                efi_bounce_buffer + EFI_LOADER_BOUNCE_BUFFER_SIZE);
> >+#endif
>
> Adding a debug message here is ok.
>
> But writing "warning" in a debug message which is just printing an address for a configuration selected item looks weird to me.

I added that because you said it needed to say it was a warning. I'll
remove it and try again.

Regards,
Simon