On Mon, Jan 13, 2020 at 09:58:25PM +0200, Jari Ruusu wrote: > On 1/13/20, Luis Chamberlain <mcgrof@xxxxxxxxxx> wrote: > > So what happens with you use the built-in firmware loader for > > the Intel microcode at this time? I am surprised this issue > > wasn't reported earlier, so thanks for picking it up, but to > > be complete such a change requires a bit more information. > > > > What exactly happens now? > > Before that 16-byte alignment patch was applied, my only one > microcode built-in BLOB was "accidentally" 16-byte aligned. How did it accidentially get 16-byte aligned? Also, how do you *know* something is broken right now? I mean you issued a patch for stable. I thought you hit a panic or some issue while loading. If we are not sure this fixes a real issue as of yet, I can't see the merit for propagating a fix to stable. > After that patch was applied, new kernel System.map file was > exactly same. So, for me that patch did not change anything. > > Same 16-byte alignment before and after patch: > > $ grep " _fw_.*_bin" System.map > ffffffff81f55e90 r _fw_intel_ucode_06_8e_09_bin > > >> Fix this by forcing all built-in firmware BLOBs to 16-byte > >> alignment. > > > > That's a huge stretch, see below. > > I understand and to some degree agree. > > > So I'd like to determine first if we really need this. > > We do need it. Violating Intel specs is not good. It may be that > some processor models require aligned and some accept less > aligned. Fair point. A fix to follow the spec is however different than to say without it things don't work, and we need to propagate a fix to stable kernels. > > If set as a global new config option, we can use the same logic and > > allow an architecture override if the user / architecture kconfig > > configures it such: > > > > config ARCH_DEFAULT_FIRMWARE_ALIGNMENT > > string "Default architecture firmware aligmnent" > > "4" if 64BIT > > "3" if !64BIT > > > > config FIRMWARE_BUILTIN_ALIGN > > string "Built in firmware aligment requirement" > > default ARCH_DEFAULT_FIRMWARE_ALIGNMENT if !ARCH_CUSTOM_FIRMWARE_ALIGNMENT > > default ARCH_CUSTOM_FIRMWARE_ALIGNMENT_VAL if > > ARCH_CUSTOM_FIRMWARE_ALIGNMENT > > Some good description goes here > > > > Or something like that. > > It doesn't have to user visible config option, only default align > changed when selected set of options are enabled. Right, I didn't intend for it to be visible really. It was just an example of kconfig magic how perhaps how to define this if we needed something configurable per arch. > My patch was intentionally minimal, without #ifdef spaghetti. Thanks for it. We just need to dust it off a bit now. Luis
