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5. Ekkinhsh

Otan to susthma jekina, to BIOS diabazei ton tomea 0 (gnwstos kai ws MBR - Master Boot Record) apo ton prwto disko (h apo disketa h CD-ROM) kai diabazei ton kwdika poy briskei ekei - synh8ws enan fortwth. Ayta ta programmatakia synh8ws den periexoyn odhgous kai xrhsimopoioun to BIOS. Ayto shmainei oti o pyrhnas toy Linux mporei na fortw8ei mono otan brisketai oloklhros stoys prwtoys 1024 kylindroys.

To problhma ayto lunetai polu eukola: sigoyreyteite oti o pyrhnas (kai isws kai alla arxeia poy xreiazontai kata thn ekkinhsh, opws ta arxeia toy LILO) briskontai se mia katatmhsh poy periexetai ej oloklhroy stoys prwtoys 1024 kylindroys kai oti to BIOS mporei na exei prosbash - ayto shmainei ton prwto h deutero disko.

Etsi: dhmioyrghste mia katatmhsh, as poume 10MB, wste na yparxei xwros gia merikous pyrhnes, sigoyreuontas oti brisketai oloklhrh stoys prwtoys 1024 kylindroys toy prwtoy h deuteroy diskoy. Prosarthste thn sto /boot wste to LILO na balei o,ti xreiazetai ekei.

5.1 To LILO kai h epilogh `linear'

Allo ena shmeio sto opoio o fortwths kai to BIOS prepei na symfwnoun einai h gewmetria toy diskoy. To LILO rwta ton pyrhna gia th gewmetria, alla olo kai perissoteroi programmatistes odhgwn exoyn thn kakh synh8eia na pairnoyn th gewmetria apo ton pinaka katatmhsewn, anti na lene sto LILO ti 8a xrhsimopoiei to BIOS. Etsi, h gewmetria apo ton pyrhna einai syxna axrhsth. Se aytes tis periptwseis einai xrhsimo na balete sto LILO thn epilogh `linear'. To apotelesma einai oti to LILO de xreiazetai th gewmetria kata thn egkatastash toy fortwth alla kanei th metatroph ths grammikhs dieu8ynshs kata thn ekkinhsh. Kai giati ayto den isxuei ej orismou; Yparxei ena meionekthma: me thn epilogh `linear' to LILO den jerei gia ton ari8mo twn kylindrwn, opote den mporei na sas proeidopoihsei an meros toy pyrhna einai egkatesthmeno meta to peras twn 1024 kylindrwn kai mporei na katalhjete me ena susthma poy den jekina.

5.2 Ena bug toy LILO

Me ekdoseis toy LILO katw toy v21 yparxei ena akoma problhma: h metatroph diey8unsewn poy ginetai kata thn ekkinhsh einai problhmatikh: otan to c*H einai 65536 h parapanw, dhmioyrgeitai la8os ston ypologismo. Gia H megalutera toy 64 dhmioyrgeitai aysthrotero orio gia to c apo to gnwsto c < 1024; gia paradeigma, me H=255 kai ena palio LILO prepei na exete c < 258. (c=o kulindros opoy brisketai o pyrhnas, H=ari8mos kefalwn).

5.3 Oi 1024 kulindroi den einai 1024 kulindroi

O Tim Williams grafei: `Eixa thn katatmhsh toy Linux stoys prwtoys 1024 kylindroys kai pali den jekinouse. Mono otan to ebala prin to 1 GB doulece'. Pws ginetai ayto; Aytos htan enas SCSI diskos me AHA2940UW elegkth poy xrhsimopoiei eite H=64, S=32 (dhladh kulindroi toy 1 MiB = 1.05 MB), h H=255, S=63 (dhladh kulindroi twn 8.2 MB), analoga me tis epiloges ston disko kai to BIOS. Anamfisbhthta to BIOS ypo8etei to prwto, opote oi 1024 kulindroi ftanoyn mexri to 1 GiB, enw to Linux xrhsimopoiei to deutero kai to LILO nomize oti to orio htan sta 8.4 GB.


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