From 640e8981e85335274778cc2f3ada7eb74fa869b0 Mon Sep 17 00:00:00 2001 From: Leah Rowe Date: Sun, 27 Oct 2024 18:42:17 +0000 Subject: [PATCH] tasks page: add note about 3050micro hang workaround Signed-off-by: Leah Rowe --- site/tasks/index.md | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/site/tasks/index.md b/site/tasks/index.md index da05c48..383a767 100644 --- a/site/tasks/index.md +++ b/site/tasks/index.md @@ -1980,3 +1980,39 @@ Dell 3020 ========= another haswell. different to 9020, but could be added. + +Dell 3050 Micro century byte +============================ + +The `CONFIG_USE_LEGACY_8254_TIMER` +and `CONFIG_USE_PC_CMOS_ALTCENTURY` options must both be +enabled. Discovered in patch `d1743d1f64720801146b162c01568ca0023dfb00` +of lbmk; look at that revision and the next one after it, +revision `237fa1e3c18365794bf5bf525df99a460c821192`. + +As of that revision, SeaBIOS works normally, on Dell OptiPlex 3050 Micro. +It was hanging. Look at the patches about 10 revisions before +then, from when the 3050 was first added to lbmk. I made, at that time, +a bunch of changes to match upstream as closely as possible, +until fixing it in the above revisions. + +While SeaBIOS does indeed now work perfectly on this machine, I still +don't know why it was broken before. We have our smoking gun, but +now what needs to happen is for this bug to be re-introduced, using +the above information as reference. + +Then, follow SeaBIOS execution with serial debug, possibly inserting +print statements into parts of the SeaBIOS source code. This would be +desirable, so that SeaBIOS can be used with the above two options +turned off. + +When debugging the issue, I initially tried many things. The issue was +not to do with the SeaBIOS revision, though I also changed that to the +one used by coreboot at the time, instead of the slightly newer one that +lbmk was using; I even directly used coreboot's own SeaBIOS build, instead +of lbmk's. Weirdly, I did also try with the legacy 8254 timer enabled, but +without enabling the alt century byte option; when disabling the latter, +relative to the above commit, that's what broke SeaBIOS again. + +For now, Libreboot will leave these options enabled, but this is not +desirable.