[PATCH v3 04/11] um: Don't use vfprintf() for os_info()

[Benjamin Berg]

Hi,

On Thu, 2024-01-04 at 23:37 +0100, Richard Weinberger wrote:
> On Fri, Nov 10, 2023 at 12:03 PM <benjamin at sipsolutions.net> wrote:
> > 
> > From: Benjamin Berg <benjamin at sipsolutions.net>
> > 
> > The threads allocated inside the kernel have only a single page of
> > stack. Unfortunately, the vfprintf function in standard glibc may use
> > too much stack-space, overflowing it.
> 
> Another option is giving the helper threads more memory, we don't have
> that many.
> Did you explore this option already?

I had not really considered that.

One thing though is that userspace_tramp calls os_info while working
with the stub stack. So that also means setting STUB_DATA_PAGES to 2.
But, I suspect we may want to do that anyway eventually to fit the ever
increasing mcontext size for all the AVX512 registers and such.

As I said, I think that is fine to do.

Benjamin