On Thu Sep 17, 2026 at 3:06 AM EDT, Yoann Congal wrote: > On Wed Sep 16, 2026 at 9:55 PM CEST, Trevor Gamblin via > lists.openembedded.org wrote: >> On Wed Sep 16, 2026 at 8:15 AM EDT, Harish.Sadineni wrote: >>> From: Harish Sadineni <[email protected]> >>> >>> QEMU RISC-V hangs (qemu hang-up) when using fw_jump.elf as the >>> default BIOS while kernel debugging is enabled. This has been >>> observed with the 6.18 kernel (exact version where it was >>> introduced is not known). >>> >>> As a workaround, switch to fw_dynamic.elf when KERNEL_DEBUG is >>> enabled, which avoids the hang and works correctly with debug >>> builds. The default behaviour is unchanged and continues to use >>> fw_jump.elf when KERNEL_DEBUG is not set. >> >> It'd be good to understand exactly why this doesn't work and what changed >> upstream. I'm looking into it in a local checkout, but I probably won't have >> an >> answer for a day or two. > > Thanks Trevor! > > Harish, this patch is for master isn't it? > If that's the case, would you mind resending it witout the [wrynose] tag > so it can be picked-up there?
One of my colleagues recently ran into a similar issue working on meta-cheri, and remedied it in the same way: https://github.com/CHERI-Alliance/meta-cheri/commit/c81a323888357acc1ee244fbf8f23df4b1c1288b I went and compared kernel image sizes across four configurations: |6.18: | |lrwxrwxrwx. 2 tgamblin tgamblin 1M Sep 17 13:51 Image -> Image--6.18.52+git0+9e9d8b1f91_08edce0ecd-r0-qemuriscv64-20260917173344.bin |-rw-r--r--. 2 tgamblin tgamblin 27M Sep 17 13:51 Image--6.18.52+git0+9e9d8b1f91_08edce0ecd-r0-qemuriscv64-20260917173344.bin | |6.18, KERNEL_DEBUG = "True": | |lrwxrwxrwx. 2 tgamblin tgamblin 1M Sep 17 14:08 Image -> Image--6.18.52+git0+9e9d8b1f91_08edce0ecd-r0-qemuriscv64-20260917180541.bin |-rw-r--r--. 2 tgamblin tgamblin 33M Sep 17 14:08 Image--6.18.52+git0+9e9d8b1f91_08edce0ecd-r0-qemuriscv64-20260917180541.bin | |7.2: | |lrwxrwxrwx. 2 tgamblin tgamblin 1M Sep 17 14:33 Image -> Image--7.2.6+git0+b5d69636e3_d8a1ec518a-r0-qemuriscv64-20260917183100.bin |-rw-r--r--. 2 tgamblin tgamblin 27M Sep 17 14:33 Image--7.2.6+git0+b5d69636e3_d8a1ec518a-r0-qemuriscv64-20260917183100.bin | |7.2, KERNEL_DEBUG = "True": | |lrwxrwxrwx. 2 tgamblin tgamblin 1M Sep 17 14:15 Image -> Image--7.2.6+git0+b5d69636e3_d8a1ec518a-r0-qemuriscv64-20260917181151.bin |-rw-r--r--. 2 tgamblin tgamblin 33M Sep 17 14:15 Image--7.2.6+git0+b5d69636e3_d8a1ec518a-r0-qemuriscv64-20260917181151.bin It's no surprise that turning on debug increases the image size, but it's a little weird that 7.2 is fine when 6.18 isn't. My guess is that the content where the FDT would overlap is different. I took the time to try a memory dump from the QEMU monitor in the hanging case, and I could see the FDT magic string where some kernel data should be: 1. Do 'runqemu nographic snapshot' 2. CTRL+A then 'c' 3. Do 'pmemsave 0x82200000 0x2000 dtb_dump.bin' 4. Inspect it like: |tgamblin@megalith ~/workspace/ypbuilds/poky-qemuriscv64/build $ od -An -tx1 -N16 dtb_dump.bin |d0 0d fe ed 00 00 35 ec 00 00 00 38 00 00 23 e8 'd0 0d fe ed' is in the kernel's scripts/dtc/libfdt/fdt.h: |#define FDT_MAGIC 0xd00dfeed /* 4: version, 4: total size */ The debug case (or other kernel customizations) may increase the kernel image size to the point where we risk this overlap. I could dig a bit further, but I think it's safer to use fw_dynamic.elf in general, starting with master. There needs to be more info explaining why we did it though, both in the commit message and as a comment near the change. > > Thanks! > >> >> Trevor >>> >>> [YOCTO #16409] > FYI, I have not seen this specific error on wrynose (kernel 6.18). > >>> >>> Signed-off-by: Harish Sadineni <[email protected]> >>> --- >>> meta/conf/machine/include/riscv/qemuriscv.inc | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) > > Regards,
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