[Bug 1794922] Re: lubuntu 18.10 x86 (32bit) image fails to load "ehci-pci 0000:00:a.7: dma_direct_map_sg: overflow 0x000000016e3f3000+2048 of device mask ffffffff" repeats

** Changed in: linux (Debian)
Status: Unknown => Confirmed

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https://bugs.launchpad.net/bugs/1794922

Title:
lubuntu 18.10 x86 (32bit) image fails to load "ehci-pci 0000:00:a.7:
dma_direct_map_sg: overflow 0x000000016e3f3000+2048 of device mask
ffffffff" repeats

Status in linux package in Ubuntu:
Confirmed
Status in linux package in Debian:
Confirmed

Bug description:
-- Background --
Testing the x86 (32bit) ISO image on various machines.

After zsync download, the thumb-drive is tested ("check disk for
defects") & passes; and worked fine on two systems today (dell d610 &
hp dx6120), however

-- Issue --

dell 755 (desktop) & hp dc7700 (small form factor) it just sits at
lubuntu plymouth screen.

switching to messages, it's just the following repeating

// on dell 755
"ehci-pci 0000:00:1a.7: dma_direct_map_sg: overflow 0x000000016e3f3000+2048 of device mask ffffffff"

// on hp dc7700
"ehci-pci 0000:00:1a.7: dma_direct_map_sg: overflow 0x0000000162317000+2048 of device mask ffffffff"

NOTE: I can't copy/paste from systems, as it never completes boot; I
left it >30mins (on 755) & it just kept repeating message. I've
manually typed it; so typo's could have been made.

A discussion on #lubuntu-devel provided a possible cause (Thank you
Walter!) -

---
<wxl> guiverc: lyorian: http://debian.2.n7.nabble.com/Bug-908924-dma-direct-map-sg-overflow-on-USB-access-after-upgrade-to-kernel-4-18-td4387757.html
<wxl> seems like it's a usb issue of some kind with 4.18
---

This fits because whilst I do my testing mostly on d610 & t43 (no
issues today), I'd tested Lubuntu 18.10 before on the dell 755 with no
issues. My last test was also long enough ago to be on 4.17 kernel
(suspicion)

---
// on hp 8200 elite sff (i5-2400, 8gb, nvidia quadro 600)
[ 99.999999] ehci-pci 0000:00:1d.0:dma_direct_map_sg: overflow 0x0000000223ad7000+2048 of device mask ffffffff
errors on booting 'live' (see #16) for real
BUT
the same ISO works fine on same box when a virtual machine (Virtual box on a GNU/Linux host and "Type: Linux Version: Ubuntu (32-bit)" virtual machine)

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