Re: What device for ROMFS ?

["Marc-F. LUCCA-DANIAU" <mfld.fr@gmail.com>]

Tracked by :

https://github.com/mfld-fr/elks/issues/2

MFLD



Le 27/05/2016 à 00:36, Juan Perez-Sanchez a écrit :
> Looks good. That would be an interesting contribution to this project.
> Later, you could add Execute In Place (XIP) to this modified ROMFS.
>
> Juan
>
>
> On Thu, May 26, 2016 at 2:20 AM, Marc-F. LUCCA-DANIAU <mfld.fr@gmail.com> wrote:
>> Thanks Juan for that info.
>>
>> It helped me to find some missing #define in the setup configuration
>> reading.
>> I will commit the related fixes later (because not so many people using ROM
>> boot for ELKS :-)).
>>
>> Coding a fresh new block device is one solution, but the ROM is by nature a
>> flat and linear device (except when erasing / writting).
>>
>> So I would rather refactor the existing ROMFS to directly pick data from a
>> given area in the ROM, and that area to be described in the ELKS config,
>> like the other ROM options.
>>
>> Does it make sense ?
>>
>> MFLD
>>
>>
>> Le 24/05/2016 01:07, Juan Perez-Sanchez a écrit :
>>
>> Hello:
>>
>> For the standard case, the root device is defined by the
>> arch/i86/tools/build program (see Documentation/text/boot.txt). The
>> device number is saved in bytes 508,509 of boot sector.
>>
>> After booting, the root device number is read from that location into
>> the ROOT_DEV variable by the function setup_arch() in
>> arch/i86/kernel/system.c.
>>
>> Maybe the mkbootloader does not define the root device as expected by
>> the kernel.
>>
>> In addition, you will have to write a ROM block device driver. Also, I
>> think romfs for ELKS never reached a working status.
>>
>> Juan
>>
>>
>> On Mon, May 23, 2016 at 12:09 PM, Marc-F. LUCCA-DANIAU
>> <mfld.fr@gmail.com> wrote:
>>
>> Hello,
>>
>> In a few words: what is the device to be used for a ROMFS root ?
>>
>> More: I configured ELKS as a ROM image for an embedded system, and I run it
>> under EMU86, but I cannot figure out:
>>
>> 1- how to tell ELKS to read the ROMFS superblock from ROM address space?
>> 2- how to build a ROMFS image to put in the ROM address space?
>>
>> All my tries end up with the well known:
>>
>> $ ./emu86 -w 0xe0000 -f ../../elks/elks/arch/i86/Image -x 0xe000:0x42 -i
>>
>> $ ./pcat `cat emu86.pts`
>> Loading kernel image...
>> Console: BIOS 10x115 emulating ANSI (3 virtual consoles)
>> PC/AT class machine, inode! CPU8308K base RAM, CPUID `nd socket for in'.
>> ELKS kernel (39008 text + 4168 data + 48648 bss)
>> Kernel text at e062:0000, data at 90:0000 62 K of memory for user processes.
>> ELKS network sockets
>> TCP/IP stack by Harry Kalogirou
>> ELKS version 0.2.0
>> panic: VFS: Unable to mount root fs on 206D
>> apparent call stack:
>> Line: Addr    Parameters~~~~: ~~~~    ~~~~~~~~~~
>>     0: 1D59 => 0000 7102 0000 0000 0000 0000 0000
>>     1: 00B7 => 0000 0000 0000 0000 0000 0000 0000
>>     2: 0000 => CE50 0000 0000 0001 0000 6166 6C69
>>     3: 1048 => 0000 0000 0000 0000 0000 0000 0000
>>     4: 0000 => CE50 0000 0000 0001 0000 6166 6C69
>>     5: 1048 => 0000 0000 0000 0000 0000 0000 0000
>>     6: 0000 => CE50 0000 0000 0001 0000 6166 6C69
>>     7: 1048 => 0000 0000 0000 0000 0000 0000 0000
>>     8: 0000 => CE50 0000 0000 0001 0000 6166 6C69
>> SYSTEM LOCKED - Press CTRL-ALT-DEL to reboot:
>>
>> Any suggestion ?
>>
>> Thanks,
>>
>> MFLD
>>
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