June 2026 - SeaBIOS - mail.coreboot.org

regression: cannot boot from nvme anymore, disabling 64bit pci io window helps
by Marek Marczykowski-Górecki July 7, 2026

July 7, 2026

Hi, After an update some time ago, a VM wit 8GB RAM cannot boot from nvme anymore. QEMU cmdline: /usr/bin/qemu-system-x86_64 \ -chardev ringbuf,id=serial0,logfile=serial0,logappend=on \ -serial chardev:serial0 \ -m 8192 \ -enable-kvm \ -vnc :2,share=force-shared \ -blockdev driver=file,node-name=hd0-file,filename=disk.qcow2,cache.no-flush=on,discard=unmap \ -blockdev driver=qcow2,node-name=hd0,file=hd0-file,cache.no-flush=on,discard=unmap \ -device nvme,id=hd0-device,drive=hd0,serial=hd0 \ -chardev stdio,id=seabios -device isa-debugcon,iobase=0x402,chardev=seabios \ -bios /home/user/seabios/out/bios.bin There is nothing fancy on the disk, just standard grub2 setup, but also I believe it doesn't matter, as it doesn't even reach grub. When it fails, the seabios log contains: PCI: 64: 0000038000000000 - 0000038040000000 PCI: map device bdf=00:04.0 bar 0, addr 38000000000, size 00004000 [mem] ... Searching bootorder for: /pci@i0cf8/isa@1/fdc@03f0/floppy@0 ATA controller 1 at 1f0/3f4/0 (irq 14 dev 9) ATA controller 2 at 170/374/0 (irq 15 dev 9) Searching bootorder for: HALT Can not map memory bar over 4Gig ... Boot failed: could not read the boot disk Working version has this instead: PCI: map device bdf=00:04.0 bar 0, addr febf0000, size 00004000 [mem] ... Booting from Hard Disk... Booting from 0000:7c00 00:04.0 is the nvme. I'm attaching full logs for both cases. Bisect shows: 96a8d130a8c2e908e357ce62cd713f2cc0b0a2eb is the first bad commit commit 96a8d130a8c2e908e357ce62cd713f2cc0b0a2eb (HEAD) Author: Gerd Hoffmann <kraxel(a)redhat.com> Date: Fri Sep 9 10:17:15 2022 +0200 be less conservative with the 64bit pci io window Current seabios code will only enable and use the 64bit pci io window in case it runs out of space in the 32bit pci mmio window below 4G. This patch will also enable the 64bit pci io window when (a) RAM above 4G is present, and (b) the physical address space size is known, and (c) seabios is running on a 64bit capable processor. This operates with the assumption that guests which are ok with memory above 4G most likely can handle mmio above 4G too. In case the 64bit pci io window is enabled also assign more memory to prefetchable pci bridge windows and the complete 64bit pci io window. The total mmio window size is 1/8 of the physical address space. Minimum bridge windows size is 1/256 of the total mmio window size. Signed-off-by: Gerd Hoffmann <kraxel(a)redhat.com> I've tried the recent "[PATCH] limit address space used for pci devices, part two" patch from the ML, but it doesn't help. OTOH, the series with "only enable 64bit pci io window when RAM >64G" does help. -- Best Regards, Marek Marczykowski-Górecki Invisible Things Lab

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[PATCH] vbe: fix Set Window return status in linear mode
by Daniel Verkamp June 14, 2026

June 14, 2026

VBE function 05h (Display Window Control) is not allowed while a linear framebuffer mode is set. However, the return status code for this case was not fully filled out: only the AH register was filled out, but AL was left unchanged from its original function 05h value, resulting in a status code of 0x0305, whereas the correct status would be 0x034F (indicating that the function is supported but is invalid in the current mode). This may be a result of a too-literal reading of the VBE specification; when describing the behavior of this function when called in a linear mode, it says "the function must fail with completion code AH=03h", not mentioning the value of AL. However, the general "VBE Return Status" section still applies, which indicates that AL should be set to 4Fh on return if the function is supported. Additionally, the patch changes the status code assignment to use a hex literal instead of a constant, since this is consistent with all of the other status code assignments in the VBE code. Signed-off-by: Daniel Verkamp <daniel(a)drv.nu> --- vgasrc/vbe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/vgasrc/vbe.c b/vgasrc/vbe.c index 2ae0a980..67162d97 100644 --- a/vgasrc/vbe.c +++ b/vgasrc/vbe.c @@ -257,7 +257,7 @@ vbe_104f05(struct bregs *regs) if (regs->bh > 1 || regs->bl > 1) goto fail; if (GET_BDA_EXT(vbe_mode) & MF_LINEARFB) { - regs->ah = VBE_RETURN_STATUS_INVALID; + regs->ax = 0x034f; return; } struct vgamode_s *curmode_g = get_current_mode(); -- 2.54.0

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Re: [PATCH] vbe: fix Set Window return status in linear mode
by Валентин June 3, 2026

June 3, 2026

Maybe use "regs->ax = (VBE_RETURN_STATUS_INVALID << 8) | VBE_RETURN_STATUS_SUPPORTED;"? With best regards, Valentine. -------- Исходное сообщение --------От: Daniel Verkamp <daniel(a)drv.nu> Дата: 03.06.2026 05:47 (GMT+03:00) Кому: seabios(a)seabios.org Тема: [SeaBIOS] [PATCH] vbe: fix Set Window return status in linear mode VBE function 05h (Display Window Control) is not allowed while a linearframebuffer mode is set. However, the return status code for this casewas not fully filled out: only the AH register was filled out, but ALwas left unchanged from its original function 05h value, resulting in astatus code of 0x0305, whereas the correct status would be 0x034F(indicating that the function is supported but is invalid in the currentmode).This may be a result of a too-literal reading of the VBE specification;when describing the behavior of this function when called in a linearmode, it says "the function must fail with completion code AH=03h", notmentioning the value of AL. However, the general "VBE Return Status"section still applies, which indicates that AL should be set to 4Fh onreturn if the function is supported.Additionally, the patch changes the status code assignment to use a hexliteral instead of a constant, since this is consistent with all of theother status code assignments in the VBE code.Signed-off-by: Daniel Verkamp <daniel(a)drv.nu>--- vgasrc/vbe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/vgasrc/vbe.c b/vgasrc/vbe.cindex 2ae0a980..67162d97 100644--- a/vgasrc/vbe.c+++ b/vgasrc/vbe.c@@ -257,7 +257,7 @@ vbe_104f05(struct bregs *regs) if (regs->bh > 1 || regs->bl > 1) goto fail; if (GET_BDA_EXT(vbe_mode) & MF_LINEARFB) {- regs->ah = VBE_RETURN_STATUS_INVALID;+ regs->ax = 0x034f; return; } struct vgamode_s *curmode_g = get_current_mode();-- 2.54.0_______________________________________________SeaBIOS mailing list -- seabios(a)seabios.orgTo unsubscribe send an email to seabios-leave(a)seabios.org

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