On Wed, Mar 24, 2021 at 1:26 AM Valdis Klētnieks <valdis.kletni...@vt.edu> wrote:
> On Tue, 23 Mar 2021 22:36:33 -0400, Aruna Hewapathirane said: > > > I also see: > > CC drivers/cpufreq/cpufreq_ondemand.o > > drivers/cpufreq/cpufreq_ondemand.c: In function ‘od_set_powersave_bias’: > > drivers/cpufreq/cpufreq_ondemand.c:446:1: warning: the frame size of 1032 > > bytes is larger than 1024 bytes [-Wframe-larger-than=] > > 446 | } > > | ^ > > This is what causes the compile time errors with possible missing > firmware > > No it's not. That's just a *warning* and doesn't stop the build. The > reason > that we have that warning is because on most architectures, the entire > kernel > stack has to fit into 2 contiguous 4k pages. > > Oh dear that's right it does not stop the build what was I thinking .. > And a perfectly legal stack can be something like TCP delivering an NFS > packet > which then goes to the NFS code, which then hands it off to the VFS layer, > which checks the page cache, which hands it off to XFS, which schedules > I/O to > the filesystem, which gets handed to the block subsystem, which realizes > that > the target partition is an LVM partition, and LVM realizes that the > "physical > volume" is actually a dm-crypt, and then dm-crypt does some cryptography > and > calls the block subsystem to write to the physical disk. Feel free to > check the code > path yourself... :) > > Oh my... and oh dear ( again! ) > And all of that has to fit in 8K of stack. That's why we warn when things > have > a large stack frame entry. > I still don't understand why the 8K barrier ? Why can't we make it say 16K ? > > Anyhow, "possible missing firmware" isn't even at compile time - it's > during > the build of the initramfs at *install* time. And the most likely cause of > that is that missing external firmware that's not GPL - it's all confined > to 2 > graphics drivers - amdgpu and i915, so not at all related to a warning > against > cpufreq... > > Understood and my apologies :-)
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