[PATCH v2] CONFIG_NR_DRAM_BANKS: Remove unreferenced code as its always defined
Pali Rohár
pali at kernel.org
Tue Aug 11 18:19:41 CEST 2020
On Tuesday 11 August 2020 10:58:47 Tom Rini wrote:
> On Tue, Aug 11, 2020 at 03:22:48PM +0200, Pali Rohár wrote:
> > On Tuesday 11 August 2020 09:08:33 Tom Rini wrote:
> > > On Tue, Aug 11, 2020 at 02:39:53PM +0200, Stefan Roese wrote:
> > > > Hi Pali,
> > > >
> > > > On 11.08.20 10:00, Pali Rohár wrote:
> > > > > Hello!
> > > > >
> > > > > On Tuesday 11 August 2020 08:37:46 Stefan Roese wrote:
> > > > > > Hi Tom,
> > > > > > Hi Pali,
> > > > > >
> > > > > > (added Pali because of the Nokia RX51 issue)
> > > > >
> > > > > Could you please send me a link to "problematic" patch? As you have not
> > > > > inlined it in this email.
> > > >
> > > > https://gitlab.denx.de/u-boot/custodians/u-boot-marvell/-/commit/7196447f2e708a83c653f39c97f2439960482ad6
> > > >
> > > > Its a rebase of the original patch.
> > > >
> > > > > > On 07.08.20 21:21, Tom Rini wrote:
> > > > > > > On Thu, Jul 30, 2020 at 12:51:10PM +0200, Stefan Roese wrote:
> > > > > > >
> > > > > > > > Since commit 86cf1c82850f ("configs: Migrate CONFIG_NR_DRAM_BANKS") &
> > > > > > > > commit 999a772d9f24 ("Kconfig: Migrate CONFIG_NR_DRAM_BANKS"),
> > > > > > > > CONFIG_NR_DRAM_BANKS is always defined with a value (4 is default).
> > > > > > > > It makes no sense to still carry code that is guarded with
> > > > > > > > "#ifndef CONFIG_NR_DRAM_BANKS" (and similar). This patch removes
> > > > > > > > all these unreferenced code paths.
> > > > > > > >
> > > > > > > > Also complete remove bi_memstart & bi_memsize from the board-info
> > > > > > > > struct. As now bi_dram[] is always enabled and should be used instead.
> > > > > > > > This removes the redundant varriables.
> > > > > > > >
> > > > > > > > Signed-off-by: Stefan Roese <sr at denx.de>
> > > > > > > > Cc: Daniel Schwierzeck <daniel.schwierzeck at gmail.com>
> > > > > > > > Cc: Tom Rini <trini at konsulko.com>
> > > > > > > > Cc: Ramon Fried <ramon.fried at gmail.com>
> > > > > > > > Cc: Simon Glass <sjg at chromium.org>
> > > > > > > > Cc: Michal Simek <michal.simek at xilinx.com>
> > > > > > > > Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck at gmail.com>
> > > > > > >
> > > > > > > I don't see quite how, but this is breaking running
> > > > > > > test/nokia_rx51_test.sh (or, my fixup of this to apply to current master
> > > > > > > was wrong, and is what's breaking the test). Please rebase and confirm
> > > > > > > that test passes as well, thanks!
> > > > > >
> > > > > > I've checked the issue with nokia_rx51_test.sh and could not find any
> > > > > > issues in the patch. My assumption now is, that the very old Linux
> > > > > > kernel (2.6.28) that is used in this Nokia test, still uses the bd_info
> > > > > > struct in Linux to pass the memory information (via bd_memstart &
> > > > > > bi_memsize), as was also done in the very old PowerPC days. With this
> > > > > > patch now and the removal of these fields from bd_info, this might
> > > > > > explain why this kernel does not boot any more (no output on the serial
> > > > > > console at all).
> > > > > >
> > > > > > Pali, could you please check if my assumption is correct here? And if
> > > > > > yes, could please switch the test to using a newer kernel version? Or
> > > > > > remove the Linux kernel booting from the test?
> > > > >
> > > > > Yes, Nokia N900 uses "old" ATAGs. But we cannot remove it. New kernel
> > > > > version does not contain Maemo patches which are required for Maemo
> > > > > system which is still widely used. And yes, people are using it with
> > > > > U-Boot.
> > > > >
> > > > > Second reason why we cannot remove support for ATAGs is that Nokia's
> > > > > signed first stage bootloader pass other setup data via ATAGs for kernel
> > > > > and U-Boot N900 board code parses it, reuse it and pass to kernel.
> > > > >
> > > > > And replacing first stage bootloader is not possible because it is
> > > > > signed and signing keys are secret (now probably lost).
> > > >
> > > > Okay. But this patch is not removing ATAG support, but removes 2
> > > > member from the bd_info struct (bi_memstart & bi_memsize), which are
> > > > replaced (superseeded) by the bi_dram[].start/.size values. And AFAICT,
> > > > the generation of the memory ATAG is already done based on these
> > > > values:
> > > >
> > > > setup_memory_tags() in arch/arm/lib/bootm.c
> > > >
> > > > So I still fail to understand, why booting of this old kernel using
> > > > ATAGs does not work with this patch applied. Perhaps you could give
> > > > it a quick test? That would be really helpful. Here again the gitlab
> > > > branch that you can use for some tests:
> > > >
> > > > https://gitlab.denx.de/u-boot/custodians/u-boot-marvell/-/commits/remove-config-nr-dram-banks-v3-2020-08-11
> >
> > I can do some tests on real N900 device at the end of week. But I doubt
> > that I could debug something on device if kernel does not print any
> > message.
> >
> > Running u-boot and kernel in N900 emulator with debug serial console is
> > easier and you can do it too locally. If you look at that test script
> > test/nokia_rx51_test.sh you could see that it downloads & compile qemu
> > and prepare OneNAND MTD image with compiled u-boot + kernel binary.
> >
> > You can also run that test script locally, it does not require root and
> > all data it stores into temporary "nokia_rx51_tmp" directory. This could
> > help you to test your changes without need to push them to travis/gitlab
> > ci testing.
> >
> > > So, I also thought maybe changing bd_t was it, and reverted just that
> > > part locally, and it was still breaking. It's also only breaking in one
> > > of the three boot tests, if I follow things correctly.
> >
> > What about trying to *not* remove first two members of struct bd_info?
> > Maybe it is part of ABI structure?
> > https://gitlab.denx.de/u-boot/custodians/u-boot-marvell/-/commit/7196447f2e708a83c653f39c97f2439960482ad6#688c66555c917f123c1d054aabd1c7023c6c4522_31_30
>
> Not changing the structure is what I tried and it still failed, unless I
> made a thinko when I was checking it out. Can you please look in to
> this a bit?
Yes, I looked at that patch and seems it is really breaking something
related to dram banks.
I applied following debug patch
diff --git a/common/board_f.c b/common/board_f.c
index 51e9544b8e..ae6d37b574 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -9,6 +9,8 @@
* Marius Groeger <mgroeger at sysgo.de>
*/
+#define DEBUG
+
#include <common.h>
#include <bloblist.h>
#include <bootstage.h>
@@ -603,9 +606,17 @@ int setup_bdinfo(void)
{
struct bd_info *bd = gd->bd;
+ debug("Calling setup_bdinfo\n");
+
+ debug("CONFIG_NR_DRAM_BANKS is %u\n", CONFIG_NR_DRAM_BANKS);
+
+ debug("Previous bd->bi_dram[0].start=%u bd->bi_dram[0].size=%u\n", bd->bi_dram[0].start, bd->bi_dram[0].size);
+
bd->bi_dram[0].start = gd->ram_base; /* start of memory */
bd->bi_dram[0].size = gd->ram_size; /* size in bytes */
+ debug("New bd->bi_dram[0].start=%u bd->bi_dram[0].size=%u\n", bd->bi_dram[0].start, bd->bi_dram[0].size);
+
if (IS_ENABLED(CONFIG_SYS_HAS_SRAM)) {
bd->bi_sramstart = CONFIG_SYS_SRAM_BASE; /* start of SRAM */
bd->bi_sramsize = CONFIG_SYS_SRAM_SIZE; /* size of SRAM */
and run u-boot in qemu n900 emulator. It printed following:
Calling setup_bdinfo
CONFIG_NR_DRAM_BANKS is 2
Previous bd->bi_dram[0].start=2147483648 bd->bi_dram[0].size=134217728
New bd->bi_dram[0].start=2147483648 bd->bi_dram[0].size=268435456
So it looks like that Stefan's patch is overwriting bi_dram with
incorrect value. It sets only bi_diram[0] (first member) even there are
two banks.
I applied following patch on top of Stefan's
diff --git a/common/board_f.c b/common/board_f.c
index 51e9544b8e..d6bf23e397 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -603,8 +606,10 @@ int setup_bdinfo(void)
{
struct bd_info *bd = gd->bd;
+#if 0
bd->bi_dram[0].start = gd->ram_base; /* start of memory */
bd->bi_dram[0].size = gd->ram_size; /* size in bytes */
+#endif
if (IS_ENABLED(CONFIG_SYS_HAS_SRAM)) {
bd->bi_sramstart = CONFIG_SYS_SRAM_BASE; /* start of SRAM */
and then booting Maemo kernel started working.
So this just prove that above overwriting of bd->di_dram is incorrect
or incomplete.
For me the most suspicious is why Stefan's patch is overwriting only
bd->bi_dram[0] even when CONFIG_NR_DRAM_BANKS is set to 2.
It looks like that for OMAP3 is bi_dram structure filled by function
dram_init_banksize() from file arch/arm/mach-omap2/omap3/sdrc.c
I hope that these information helps you to debug and fix Stefan patch.
Now thanks to nokia_rx51_test.sh it is easy to test and debug all
changes for N900 in simulator. Moreover it is possible to use gdb to
connect to qemu which in which is running u-boot. So these kind of
problems should be possible to debug without real N900 hw, just in qemu
and gdb.
More information about the U-Boot
mailing list