breakpoint not working in do_mmc_read (using qemu)

breakpoint not working in do_mmc_read (using qemu)

[Chan Kim]

Hello, u-boot experts,

 

I need to modify a proprietary SD card host controller driver to be used in u-boot and I wanted to see the driver interface with the u-boot using qemu.

Trying to run u-boot on qemu with SD card, I found this nice question : https://stackoverflow.com/questions/46239926/booting-kernel-from-sd-in-qemu-arm-with-u-boot

So I followed it and saw ‘mmc rescan’, ‘mmc read’ command works.

Using debugger (arm-none-eabi-gdb), I can follow the code from _start and can set breakpoint at board_init_f and etc. 

But even if I set breakpoint at do_mmc_read or do_mmc_rescan, the breakpoint for those functions are not working.

Could anyone tell me what I’m doing wrong? (Are there things I should set in the config?)

The qemu command is this :

qemu-system-arm -machine vexpress-a9 -cpu cortex-a9 -m 128M -dtb ~/prj/abdsn/ab21sim/ab21tsim/LinuxDevDrv/linux-5.4.21/arch/arm/boot/dts/vexpress-v2p-ca9.dtb -kernel u-boot -sd sd.img -nographic -s -S

and the u-boot (ELF file) contains debug_info.

Any help will be deeply appreciated.

Thanks,

Chan Kim

p.s. BTW, this email list contains mostly PATCH emails between u-boot developers, so I feel a little sorry to ask questions here. 😊

 

RE: breakpoint not working in do_mmc_read (using qemu)

[Chan Kim]

Hi,

(for those who don't know how to stop at breakpoints after relocation..)
I came back to this problem today and found https://shenki.github.io/debugging-u-boot-after-relocation/. 

So by doing in gdb,

b relocation_done
(after you stop at relocation_done),
print /x ((gd_t *)$r9)->relocaddr
$1 = 0x67f6b000
Add-symbo-file u-boot $1
(type y)
c (continue)

Now you can stop at board_init_r or do_mmc_read!
Hope that helps.
Thanks

Chan Kim


> -----Original Message-----
> From: U-Boot <u-boot-bounces@lists.denx.de> On Behalf Of Chan Kim
> Sent: Friday, October 22, 2021 5:19 PM
> To: U-Boot Mailing List <u-boot@lists.denx.de>
> Subject: breakpoint not working in do_mmc_read (using qemu)
> 
> Hello, u-boot experts,
> 
> 
> 
> I need to modify a proprietary SD card host controller driver to be used
> in u-boot and I wanted to see the driver interface with the u-boot using
> qemu.
> 
> Trying to run u-boot on qemu with SD card, I found this nice question :
> https://stackoverflow.com/questions/46239926/booting-kernel-from-sd-in-
> qemu-arm-with-u-boot
> 
> So I followed it and saw ‘mmc rescan’, ‘mmc read’ command works.
> 
> Using debugger (arm-none-eabi-gdb), I can follow the code from _start and
> can set breakpoint at board_init_f and etc.
> 
> But even if I set breakpoint at do_mmc_read or do_mmc_rescan, the
> breakpoint for those functions are not working.
> 
> Could anyone tell me what I’m doing wrong? (Are there things I should set
> in the config?)
> 
> The qemu command is this :
> 
> qemu-system-arm -machine vexpress-a9 -cpu cortex-a9 -m 128M -dtb
> ~/prj/abdsn/ab21sim/ab21tsim/LinuxDevDrv/linux-
> 5.4.21/arch/arm/boot/dts/vexpress-v2p-ca9.dtb -kernel u-boot -sd sd.img -
> nographic -s -S
> 
> and the u-boot (ELF file) contains debug_info.
> 
> Any help will be deeply appreciated.
> 
> Thanks,
> 
> Chan Kim
> 
> p.s. BTW, this email list contains mostly PATCH emails between u-boot
> developers, so I feel a little sorry to ask questions here. 😊
> 
>