From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adam Ford Date: Sun, 10 Jan 2021 06:07:08 -0600 Subject: [PATCH 1/1] image: usage of value ~0UL for intrd_high In-Reply-To: <9E577567-B784-43D3-9DC5-EAEAD2131C55@gmx.de> References: <20210109180617.42030-1-xypron.glpk@gmx.de> <20210109185836.GJ2292@bill-the-cat> <20210109194004.GK2292@bill-the-cat> <20210109212301.GL2292@bill-the-cat> <9E577567-B784-43D3-9DC5-EAEAD2131C55@gmx.de> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Sat, Jan 9, 2021 at 5:23 PM Heinrich Schuchardt wrote: > > Am 9. Januar 2021 22:23:01 MEZ schrieb Tom Rini : > >On Sat, Jan 09, 2021 at 08:59:01PM +0100, Heinrich Schuchardt wrote: > >> Am 9. Januar 2021 20:40:04 MEZ schrieb Tom Rini : > >> >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 > >> > 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. > > > Who would understand that? > > All 1s that is 111111111? > > We need something a non-developer will grasp. Copying the exact value from the readme is the easiest thing to do and the least typo prone. What about -1? adam > > Best regards > > Heinrich > > >> >> > > >> >> > 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 Is it for some outdated Linux release?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. >