From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Harvey Date: Fri, 9 Apr 2021 17:29:36 -0700 Subject: [PATCH] Revert "spl: Drop bd_info in the data section" In-Reply-To: <20210409205312.GL1310@bill-the-cat> References: <20210408165611.1195887-1-mr.nuke.me@gmail.com> <23de53fe-e0be-9fe8-1e59-fd1e0a2104d6@gmail.com> <20210409205312.GL1310@bill-the-cat> 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 Fri, Apr 9, 2021 at 1:53 PM Tom Rini wrote: > > On Fri, Apr 09, 2021 at 03:24:41PM -0500, Adam Ford wrote: > > On Fri, Apr 9, 2021 at 2:20 PM Alex G. wrote: > > > > > > Hi Simon > > > > > > On 4/8/21 6:55 PM, Simon Glass wrote: > > > > Hi Alexandru, > > > > > > > > On Fri, 9 Apr 2021 at 04:56, Alexandru Gagniuc wrote: > > > >> > > > >> This reverts commit 38d6b7ebdaee3e0e8426ef1b9df88bdce8ae2e75. > > > >> > > > >> struct global_data contains a pointer to the bd_info structure. This > > > >> pointer was populated spl_set_bd() to a pre-allocated bd_info in the > > > >> ".data" section. The referenced commit replaced this mechanism to one > > > >> that uses malloc(). That new mechanism is only used if SPL_ALLOC_BD=y. > > > >> which very few boards do. > > > >> > > > >> The result is that (struct global_data)->bd is NULL in SPL on most > > > >> platforms. This breaks falcon mode, since arch_fixup_fdt() tries to > > > >> access (struct global_data)->bd and set the "/memory" node in the > > > >> devicetree. The result is that the "/memory" node contains garbage > > > >> values, causing linux to panic() as it sets up the page table. > > > >> > > > >> Instead of trying to fix the mess, potentially causing other issues, > > > >> revert to the code that worked, while this change is reworked. > > > > > > > > The goal here is to drop a feature that few boards use and reduce > > > > memory usage in SPL. It has been in place for two releases now. > > > > > > > > If Falcon mode needs it, perhaps you could add an 'imply' in the > > > > Kconfig for that feature? Is there one? Or perhaps > > > > CONFIG_ARCH_FIXUP_FDT_MEMORY ? > > > > > > > > One option would be to return an error in arch_fixup_fdt(). In > > > > general, fixups make things tricky because there is no way to > > > > determine when they are used but at least this one has a CONFIG. > > > > > > > > > > The argument that this has been in place for two releases is incorrect. > > > Commit 38d6b7ebdaee3e0e8426ef1b9df88bdce8ae2e75 was only introduced with > > > the v2021.04 release. It definitely was not in 2021.01. It's only in the > > > last release, which is four days old t the time of this writing. > > Yes. But another way of saying that is that we're 4 days in to the > merge window. That's a bit early to say we must revert the change. If > this was just before the release, yes, revert would be the right answer. > It's also the case the original commit fixes some cases while also > saving size, if I read it right. So a strict revert isn't right, we'd > need to also probably also default y SPL_ALLOC_BD in some cases. > > > > Although I was able to find one example, the reality is that we don't > > > know the full extent of the breakage. The prudent thing at this point is > > > to revert. > > > > > > The knowledge of how to init the platform is in the devicetree and code. > > > Why should kconfig also be involved in storing this knowledge? By this > > > model, as the number of boards increases without bounds, every "if" > > > predicate tends to be Kconfig driven. That is not maintainable, and why > > > I think the original change --and the proposed fixes-- are broken by design. > > > > > > Furthermore, I'm happy to discuss what to do about Falcon mode, and if > > > we should kill it entirely (I have an alternative proposal). But we > > > shouldn't have that discussion in a manner holding my platform hostage. > > > To be fair to you, I don't think reverting a 64-byte savings in .data > > > will hold your platform hostage either. > > > > That original patch broke a bunch of OMAP boards, but enabling > > SPL_ALLOC_BD was the solution to fix the issue. > > Can you try enabling SPL_ALLOC_BD and see if that fixes it? Maybe we > > can make falcon mode imply it. > > It would be "select" since it needs it rather than imply. > I just ran into this as well finding that commit 38d6b7ebdaee ("spl: Drop bd_info in the data section") breaks Gateworks Ventana and defining SPL_ALLOC_BD does resolve it. In this case, Falcon mode is not being used and the breakage is because arch/arm/mach-imx/spl.c dram_init_banksize() accesses gd->bd which is NULL. So I would guess that this probably broke a whole lot of IMX based boards that use SPL. I don't quite know what the best solution is... we now have a v2021.04 that is broken for several or many boards and I dont' know if its clear what cases break. Best regards, Tim