On Fri, Apr 05, 2013 at 09:17:40PM +0200, Albert ARIBAUD wrote:
Hi Tom,
On Fri, 5 Apr 2013 13:55:21 -0400, Tom Rini trini@ti.com wrote:
On Fri, Apr 05, 2013 at 07:32:54PM +0200, Beno??t Th??baudeau wrote:
Hi Tom,
On Friday, April 5, 2013 6:00:30 PM, Tom Rini wrote:
On Fri, Apr 05, 2013 at 03:56:46PM +0200, Beno??t Th??baudeau wrote:
Hi Albert,
On Friday, April 5, 2013 8:00:43 AM, Albert ARIBAUD wrote:
Hi Beno??t,
[snip]
IIUC, this future patch would increase the limit for SPL run-time size, as the constant against which the ASS tests __bss_end for would necessarily be greater than it is now. Correct? If so, this future patch should not break any target, as it would loosen the constraint, not tighten it.
Yes, it would either be the same or relaxed a bit, depending on the chosen option:
- Define CONFIG_SPL_BSS_MAX_SIZE and test against CONFIG_SPL_MAX_SIZE + CONFIG_SPL_BSS_MAX_SIZE, the sum remaining the same as or being larger than currently, depending on the new values for CONFIG_SPL_MAX_SIZE and CONFIG_SPL_BSS_MAX_SIZE.
- Define a new config meaning text + data + rodata + bss (e.g. CONFIG_SPL_MAX_RAM_SIZE or CONFIG_SPL_MAX_MEM_FOOTPRINT), and just replace CONFIG_SPL_MAX_SIZE with it for the users of arch/arm/cpu/u-boot*.lds, taking care that this was the only meaning those users were giving to CONFIG_SPL_MAX_SIZE.
The first option would probably be preferable, using the same value for CONFIG_SPL_MAX_SIZE, and a non-zero value for CONFIG_SPL_BSS_MAX_SIZE.
I think the problem is that Tegra really needs the second case as their constraint is "must fit below next part of payload". We can assume the users of that linker script today care about footprint and update their define I believe. da850evm and the rest of the davinci platforms would also be a case to convert to this, but the omap*/am3* platforms would not.
Yes, then let's have an assert in arch/arm/cpu/u-boot*.lds with a different config name (as in option 2 above) just for Tegra, and another assert for CONFIG_SPL_MAX_SIZE against __bss_start.
And all users of CONFIG_SPL_MAX_SIZE should be checked to make sure that there is not another special case somewhere.
I didn't audit the PowerPC targets, but on ARM we have, roughly:
- Tegra (covered in Stephen's email, and in short, must include BSS in size check) which uses SPL_MAX_SIZE to include BSS
- OMAP*/AM3* which does not constrain BSS to SPL_MAX_SIZE
- DaVinci which must also constrain BSS to the initial RAM, but for different reasons.
- iMX which also uses SPL_BSS_MAX to cover the BSS separate from the rest of the program.
How about this?
In the u-boot*.lds files, doing separate asserts for SPL and SPL BSS max size, with the SPL assert being further divided in two cases depending on BSS max size being defined or not:
#if defined(CONFIG_SPL_MAX_SIZE) #if defined(CONFIG_SPL_BSS_MAX_SIZE) ASSERT( __bss_end - __image_copy_start < (CONFIG_SPL_TEXT_BASE + \ CONFIG_SPL_MAX_SIZE), "SPL image code+BSS too big"); #else ASSERT( __bss_end - __image_copy_start < CONFIG_SPL_TEXT_BASE, \ CONFIG_SPL_MAX_SIZE), "SPL image code too big"); #endif
#if defined(CONFIG_SPL_BSS_MAX_SIZE) ASSERT( __bss_end - __bss_start < CONFIG_SPL_TEXT_BASE, \ CONFIG_SPL_BSS_MAX_SIZE), "SPL image BSS too big"); #endif #endif
I think this is too complicated. Our cases are: 1. text/data/rodata/bss MUST fit within $size for $location 2. text/data/rodata MUST fit within $sizeA for $locationA and BSS must start at $locationB (which is at least $sizeB big)
The problem is that CONFIG_SPL_MAX_SIZE is defined to mean #2 but the generic ARM SPL linker script was using it for #1. We should correct the generic ARM SPL linker script to test #2, and add in a new option to cover #1 and convert tegra (as they're the user of the generic script) to this new option.
- Defining CONFIG_SPL_BSS_MAX_SIZE only for Tegra, Davinci, IMX (where CONFIG_SPL_BSS_MAX_SIZE is actually the gap size)
No, this is wrong. These do not care about the BSS size, they care about the text/data/rodata/bss size.
- *Not* defining CONFIG_SPL_MAX_SIZE or CONFIG_SPL_BSS_MAX_SIZE for OMAP*/AM3*
This is wrong. The main reason for SPL_BSS_MAX_SIZE here is that we have the BSS at a very different location from the rest of the binary (text/data/rodata at 0x4... BSS at 0x8...) and use MEMORY constructs to place things correctly. So we must(?) define a start and end, and that's what BSS_MAX_SIZE is for.
- Adjusting README descriptions of CONFIG_SPL_[BSS_]MAX_SIZE and ensuring Makefile uses the right size for --pad-to, as well as the few other files which use CONFIG_SPL_MAX_SIZE.
Yes, we need to audit README and users after all of this.