On 1/9/21 10:23 PM, Tom Rini wrote:
On Sat, Jan 09, 2021 at 08:59:01PM +0100, Heinrich Schuchardt wrote:
Am 9. Januar 2021 20:40:04 MEZ schrieb Tom Rini trini@konsulko.com:
On Sat, Jan 09, 2021 at 08:33:40PM +0100, Heinrich Schuchardt wrote:
On 1/9/21 7:58 PM, Tom Rini wrote:
On Sat, Jan 09, 2021 at 08:47:07PM +0200, Andy Shevchenko wrote:
On Sat, Jan 9, 2021 at 8:06 PM Heinrich Schuchardt
xypron.glpk@gmx.de wrote:
> > The comment for initrd_high in the coding and in README were
contradicting
> and neither fully described what the coding does. > > Clarify the usage of the special value ~0UL for the environment
variable
> initrd_high.
All those F:s are hard to read in the comments and documentation
and
typo prone. I would prefer to rephrase like "all 1:s value in 32-
or
64-bit format" or alike.
If we're going to improve this we should also note it's discouraged unless you know for certain there will be no overlap and it's
strongly
discouraged in default environments.
What exactly is discouraged?
- setting initrd_high to a value != ~0? Here I would agree.
- setting intird_high to ~0? Why should we copy initrd to a different place? Is it for some outdated Linux release?
We should always default to allowing the initrd to be relocated because we can see (in many cases) overlap that will lead to failure to boot but this forces us to ignore that. Having good default load values means we don't have a problem here.
We have an initrd that is already in memory. What could it overlap with that is not already overwritten?
Having the kernel and initrd too close in memory has the kernel BSS overwrite the initrd. This has happened time and time again before I went around making some platforms have reasonable (ie kernel early, ramdisk in lowmem but beyond where a kernel+bss can be, etc) defaults and pushing others to do the same.
Can you provide the text you want to see here?
Off-hand, it should look more like the big comment block in include/configs/ti_armv7_common.h and reference the Linux booting on arm/arm64 documents while noting that other architectures have the same fundamental issues and their exact limits may or may not be as well documented.
There is nothing in the include/configs/ti_armv7_common.h comments requiring to relocate initrd.
Best regards
Heinrich