[OSy] Problem se statickou strukturou

[Martin Cetkovský]

Ahoj,

tak jsme jeste trochu badali a deje se nasledujici. Pri zavolani metody init_memory se adresa sledovane staticke promenne zmeni z 0x80020BB8 (pred vypisem Memory) na 0x8001FED8 (po kontrole v init_memory). Vzhledem k tomu, ze mapovanou pamet mame 127 kB (do 0x1FBFF), pak az od 0x20000. Pro jistotu opakuji, ze jeste nedoslo k inicializaci pameti ani scheduleru a nebyl volan zadny malloc ani alokovan ramec (to vim s jistotou), takze IMHO nemelo sanci dojit k preplanovani ani pokropeni pameti vlastnimi silami. Opravdu mne uz nenapada, co s tim. Ma nekdo nejaky tip? Poustime to v labu.

Mame nasledujici kod:
...
puts("\n\tMemory ");
___stop();
if (someglobals.firstlock.value == 0xFFFFFFFF)
  panic("c");
init_memory();
....

void init_memory(void)
{
    unsigned int start;
    unsigned int end;
    unsigned int size;
    unsigned int * p;

    if (someglobals.firstlock.value == 0xFFFFFFFF)
  	___stop();
    ...
}

Zde je vypis v assembleru.
        Memory [msim] set trace on
[msim] g
    8000FEF8    lui   v0, 0x8002        # 0x8002=32770, v0: 0x0->0x80020000, v1: 0x0->0x400004, a0: 0x0->0x80021450, sp: 0x0->0x8000b9b8, fp: 0x0->0x8000b9b8, ra: 0x0->0x8000fef4, cp0_index: 0x00000000->0x0000002f, cp0_entryhi: 0x00000000->0x000bc000
    8000FEFC    addiu v0, v0, 0x2f0     # 0x2f0=752, v0: 0x80020000->0x800202f0
    8000FF00    lw    v1, 0x8a8(v0)     # 0x8a8=2216, v1: 0x400004->0x0
    8000FF04    addiu v0, 0, 0xffff     # 0xffffffff=65535, v0: 0x800202f0->0xffffffff
    8000FF08    bne   v1, v0, 0x4       # 0x4=4
    8000FF0C    nop
    8000FF1C    jal   +0xf544           # 0xf544=62788, ra: 0x8000fef4->0x8000ff24
    8000FF20    nop
    8000F544    addiu sp, sp, 0xffd8    # 0xffffffd8=65496, sp: 0x8000b9b8->0x8000b990
    8000F548    sw    ra, 0x24(sp)      # 0x24=36
    8000F54C    sw    fp, 0x20(sp)      # 0x20=32
    8000F550    addu  fp, sp, 0         # fp: 0x8000b9b8->0x8000b990
    8000F554    lui   v0, 0x8002        # 0x8002=32770, v0: 0xffffffff->0x80020000
    8000F558    addiu v0, v0, 0xf610    # 0xfffff610=62992, v0: 0x80020000->0x8001f610
    8000F55C    lw    v1, 0x8a8(v0)     # 0x8a8=2216, v1: 0x0->0xffffffff
    8000F560    addiu v0, 0, 0xffff     # 0xffffffff=65535, v0: 0x8001f610->0xffffffff
    8000F564    bne   v1, v0, 0x1a      # 0x1a=26
    8000F568    nop
    8000F56C    ---
[msim]

> -----Original Message-----
> From: osy-bounces at dsrg.mff.cuni.cz [mailto:osy-
> bounces at dsrg.mff.cuni.cz] On Behalf Of Martin Cetkovský
> Sent: Wednesday, December 05, 2007 2:11 PM
> To: 'Operating Systems Course'
> Subject: [OSy] Problem se statickou strukturou
> 
> Ahoj,
> 
> mame problemy se statickou strukturou, konkretne pri inicializaci
> spinlocku. Prikladam relevantni informace.
> 
> static struct{
>   ...
>    struct spinlock firstlock;
>    struct spinlock secondlock;
> } someglobals;
> 
> struct spinlock{
>   volatile int value;
> };
> 
> void spinlock_init(struct spinlock * lock)
> {
>   printk_locked("%x, %x\n", lock->value, SPINLOCK_UNLOCKED);
>   lock->value = SPINLOCK_UNLOCKED;
>   printk_locked("%x\n", lock->value);
> }
> 
> Inicializaci spinlocku volame nasledovne.
> spinlock_init(&someglobals.firstlock);
> spinlock_init(&someglobals.secondlock);
> printk_locked("after %x, value %x", &someglobals.secondlock,
> someglobals.secondlock.value);
> 
> Vypsane hodnoty jsou nasledujici (pricemz u nekolika predchozich
> jsou hodnoty spravne - 0x0 misto 0xFF*):
> 0xFFFFFFFF, 0x0
> 0xFFFFFFFF
> 0xFFFFFFFF, 0x0
> 0xFFFFFFFF
> after 0x8001FFD8, value 0xFFFFFFFFA
> 
> Bezime na single-CPU a nastava jiz pri inicializaci pameti, cili
> scheduler ani malloc se dosud nemaji sanci projevit.
> 
> Mate nekdo tip, co s tim je? Nejak to nemuzeme najit.
> 
> Diky,
> 
> Martin Cetkovský
> 
> 
> 
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