Are two partition manager for two primary partitions needed or not?

[Fabi]

Hi community,

for the partition manager I need some clarification. I've two primary partitions onto one SD card. To access both partitions, I've to setup two partition manager.  Here's the code snipped that works:

// Install partition manager over SD card driver, acquire full disk space

result = _io_part_mgr_install ( hdCard, "pm:", 0 );

         // error handling omitted here...

// Open partition manager

hdCardPart1 = fopen ( "pm:", NULL );

         // error handling omitted here...

// Validate partition 1

param = 1;

result = _io_ioctl ( hdCardPart1, IO_IOCTL_VAL_PART, &param );

if ( result == MQX_OK )

{

    // Install MFS over partition 1

    result = _io_mfs_install ( hdCardPart1, "c:", param );

             // error handling omitted here...

}

// Open file system

hd_1 = fopen ( "c:", NULL );

result = ferror ( hd_1 );

         // error handling omitted here...

// Open partition manager

hdCardPart2 = fopen ( "pm:", NULL );

         // error handling omitted here...

// Validate partition 2

param = 2;

result = _io_ioctl ( hdCardPart2, IO_IOCTL_VAL_PART, &param );

if ( result == MQX_OK )

{

    // Install MFS over partition 2

    result = _io_mfs_install ( hdCardPart2, "d:", param );

             // error handling omitted here...

}

hd_2 = fopen ( "d:", NULL );

result = ferror ( hd_2 );

         // error handling omitted here...

My question is, why two partition managers (hdCardPart1 and hdCardPart2) are needed?

That is to say, the following code snipped doesn't work:

// some code omitted here...

result = _io_mfs_install ( hdCardPart1, "c:", param );

// some code omitted here...

result = _io_mfs_install ( hdCardPart1, "d:", param ); // re-use the first partition manager for second partition -> not working

I use MQX 4.0.2.2 on MK60DN512.

TY

[RadekS · Accepted solution]

It is that way, because this is correct way.

You can have file system

1. directly on disk
2. indirectly on partition.

In second case, file system has to be installed on partition and file system doesn’t care what is below partition. Parameter partition_num will be removed in next MFS version (released probably in MQX 4.2 package).

Have a great day,
RadekS

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[Fabi]

Fine. Would it be better to distinguish the string identifier? In other words, should

hdCardPart1 = fopen ( "pm1:", NULL );

hdCardPart2 = fopen ( "pm2:", NULL );

be used instead of

hdCardPart1 = fopen ( "pm:", NULL );

hdCardPart2 = fopen ( "pm:", NULL );

or doesn't matter?

[RadekS]

In fact, you have two correct options how to select appropriate partition:

1. Select partition by string identifier
2. Select partition subsequently by ioctl command

a)

// Install partition manager over SD card driver, acquire full disk space

result = _io_part_mgr_install ( hdCard, "pm:", 0 );

hdCardPart1 = fopen ( "pm:1", NULL );

hdCardPart2 = fopen ( "pm:2", NULL );

//pm:0 is whole device; pm:1, pm:2, pm:3, pm:4 are partitions

b)

// Install partition manager over SD card driver, acquire full disk space

result = _io_part_mgr_install ( hdCard, "pm:", 0 );

hdCardPart1 = fopen ( "pm:", NULL );

partition_number = 1;

error_code = ioctl(hdCardPart1, IO_IOCTL_SEL_PART, &partition_number);

hdCardPart2 = fopen ( "pm:", NULL );

partition_number = 2;

error_code = ioctl(hdCardPart2, IO_IOCTL_SEL_PART, &partition_number);

// partition_number=0 is whole device, 1, 2, 3, 4 are partitions

I hope it helps you.