Re: [PATCH v1] MIPS: remove .bss to __rel_start overlay

[Oleksij Rempel <o.rempel@pengutronix.de>]

On 28.01.20 14:06, Peter Mamonov wrote:
> On Tue, Jan 28, 2020 at 02:55:13PM +0300, Antony Pavlov wrote:
>> On Tue, 28 Jan 2020 10:28:32 +0100
>> Oleksij Rempel <o.rempel@pengutronix.de> wrote:
>>
>> Hi!
>>
>> Looks like this patch has some undocummented side effects
>> (or in other words, it makes undocummented fixups).
>>
>> I have tested this patch on qemu-malta with current master,
>> ee8960aec018df2de ("ARM: imx6: properly check for IPU presence").
>> It works fine: memtest works, iomem output looks good.
>>
>> But the patch fixes several issues and commit message does not contain
>> any information about it.
>>
>> I rebuild current master with qemu-malta_defconfig and MMU enabled.
>>
>> I used this qemu cmdline to enable qemu monitor:
>>
>> qemu-system-mips -nodefaults -M malta -m 256 -nographic -bios barebox-flash-image
>>     -net user -net nic,model=rtl8139 -serial mon:stdio
>>
>> With '-serial mon:stdio' one can invoke qemu monitor with "ctrl-a c" keypress sequence.
>>
>> So I tried 'info registers' qemu monitor command after barebox startup:
>>
>> Hit any to stop autoboot:    3
>> barebox@qemu malta:/
>> barebox@qemu malta:/
>> barebox@qemu malta:/ iomem
>> 0x00000000 - 0xffffffff (size 0x00000000) iomem
>>    0x180003f8 - 0x180003ff (size 0x00000008) 180003f8.serial@180003f8.of
>>    0x1e000000 - 0x1e3fffff (size 0x00400000) 1e000000.flash@1e000000.of
>>    0x1f000900 - 0x1f00093f (size 0x00000040) 1f000900.serial@1f000900.of
>>    0x1f000b00 - 0x1f000b1f (size 0x00000020) 1f000b00.gpio@1f000b00.of
>>    0x80000000 - 0x8fffffff (size 0x10000000) kseg0_ram0
>> barebox@qemu malta:/ QEMU 4.2.0 monitor - type 'help' for more information
>> (qemu) info registers
>> pc=0xa081232c HI=0x00000026 LO=0x20000000 ds 0090 a081232c 1
>> GPR00: r0 00000000 at 00000000 v0 b80003f8 v1 00000000
>> GPR04: a0 a0408668 a1 b80003fd a2 b80003f8 a3 ffffffff
>> GPR08: t0 00000001 t1 00000000 t2 0000005a t3 00000023
>> GPR12: t4 00000000 t5 00010000 t6 00000040 t7 00000010
>> GPR16: s0 a0408668 s1 a085cd20 s2 a0860000 s3 a0860000
>> GPR20: s4 a0860000 s5 00000400 s6 a08613c0 s7 00000001
>> GPR24: t8 00000008 t9 a0812340 k0 00400000 k1 fffffffa
>> GPR28: gp 00000000 sp 8fb8fd10 s8 ffffffff ra a0812420
>> CP0 Status  0x00000000 Cause   0x00000400 EPC    0x00000000
>>      Config0 0x80008482 Config1 0x9e190c8f LLAddr 0x0000000000000000
>>      Config2 0x80000000 Config3 0x00000000
>>      Config4 0x00000000 Config5 0x00000000
>> (qemu) quit
>>
>> So I see several issues in current master at once:
>>
>>    * iomem output has no information on sdram regions, so memtest is unusable;
>>    * pc=0xa081232c, relocation does not work, barebox is located with 8M offset
>>      from start of RAM. The board has 256M and relocation routine
>>      should move barebox code much higher;
>>    * pc=0xa081232c, so barebox code works from KSEG1 not from KSEG0 as MMU=y option implies.
>>
>> Your patch fixes all these symptoms at ones however the commit message
>> says nothing about them.
> 
> I've tested the patch, everything looks right now:
> 
> 	barebox@qemu malta:/ iomem
> 	0x00000000 - 0xffffffff (size 0x00000000) iomem
> 	  0x180003f8 - 0x180003ff (size 0x00000008) 180003f8.serial@180003f8.of
> 	  0x1e000000 - 0x1e3fffff (size 0x00400000) 1e000000.flash@1e000000.of
> 	  0x1f000900 - 0x1f00093f (size 0x00000040) 1f000900.serial@1f000900.of
> 	  0x1f000b00 - 0x1f000b1f (size 0x00000020) 1f000b00.gpio@1f000b00.of
> 	  0x80000000 - 0x8fffffff (size 0x10000000) kseg0_ram0
> 	    0x8fb89000 - 0x8fb8ffff (size 0x00007000) stack
> 	    0x8fb90000 - 0x8ff8ffff (size 0x00400000) malloc space
> 	    0x8ff90000 - 0x8ffeae9f (size 0x0005aea0) barebox
> 	    0x8ffeaea0 - 0x8ffefadf (size 0x00004c40) barebox data
> 	    0x8fff7ae0 - 0x8fffbbdf (size 0x00004100) bss
> 	barebox@qemu malta:/ whereami
> 	code   @ 8ffb9bcc (8ffb9bc0)
> 	data   @ 8ffef3c0
> 	bss    @ 8fff9ae0
> 	heap   @ 8fbb9518
> 	stack  @ 8fb8fd50
> 	barebox@qemu malta:/
> 
> However I have to enable CONFIG_MMU after `make qemu-malta_defconfig`, or I get
> `ERROR: Error: Cannot request SDRAM region for stack`, and no barebox memory
> areas in `iomem` output.  CONFIG_MMU seems to be enabled for ath79 only:
> 
> 	$ git grep CONFIG_MMU arch/mips/configs/
> 	arch/mips/configs/ath79_defconfig:CONFIG_MMU=y
> 	$

Yes, this should be fixed in a separate patch.


Kind regards,
Oleksij Rempel

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