Tout d'abord, merci d'avoir répondu.

Je n'ai pas de /boot/config-vesion_kernel donc j'ai fait un
egrep -i scsi /usr/share/genkernel/x86/kernel-config-2.6
(apparement, la config du noyau est dans ce fichier -et pas dans /usr/src/linux/.config- quand on utilise genkernel).
et ça m'a donné:

***********************************
# NOTE: USB_STORAGE enables SCSI, and 'SCSI disk support'
# may also be needed; see USB_STORAGE Help for more information
CONFIG_USB_STORAGE=m
# CONFIG_USB_STORAGE_DEBUG is not set
CONFIG_USB_STORAGE_DATAFAB=y
CONFIG_USB_STORAGE_FREECOM=y
CONFIG_USB_STORAGE_ISD200=y
CONFIG_USB_STORAGE_DPCM=y
CONFIG_USB_STORAGE_USBAT=y
CONFIG_USB_STORAGE_SDDR09=y
CONFIG_USB_STORAGE_SDDR55=y
CONFIG_USB_STORAGE_JUMPSHOT=y
*******************************************************
La commande egrep -i scsi /usr/share/genkernel/x86/kernel-config-2.6 m'a donné :

********************************************************
# CONFIG_CISS_SCSI_TAPE is not set
# CONFIG_BLK_DEV_IDESCSI is not set
# SCSI device support
CONFIG_SCSI=y
CONFIG_SCSI_PROC_FS=y
# SCSI support type (disk, tape, CD-ROM)
# Some SCSI devices (e.g. CD jukebox) support multiple LUNs
# CONFIG_SCSI_MULTI_LUN is not set
# CONFIG_SCSI_CONSTANTS is not set
# CONFIG_SCSI_LOGGING is not set
# SCSI Transport Attributes
CONFIG_SCSI_SPI_ATTRS=m
CONFIG_SCSI_FC_ATTRS=m
# CONFIG_SCSI_ISCSI_ATTRS is not set
CONFIG_SCSI_SAS_ATTRS=m
# SCSI low-level drivers
# CONFIG_ISCSI_TCP is not set
CONFIG_SCSI_3W_9XXX=m
CONFIG_SCSI_7000FASST=m
CONFIG_SCSI_ACARD=m
CONFIG_SCSI_AHA152X=m
CONFIG_SCSI_AHA1542=m
CONFIG_SCSI_AHA1740=m
CONFIG_SCSI_AACRAID=m
CONFIG_SCSI_AIC7XXX=m
# CONFIG_SCSI_AIC7XXX_OLD is not set
CONFIG_SCSI_AIC79XX=m
CONFIG_SCSI_DPT_I2O=m
CONFIG_SCSI_IN2000=m
CONFIG_SCSI_SATA=y
CONFIG_SCSI_SATA_AHCI=m
CONFIG_SCSI_SATA_SVW=m
CONFIG_SCSI_ATA_PIIX=m
CONFIG_SCSI_SATA_MV=m
CONFIG_SCSI_SATA_NV=m
CONFIG_SCSI_PDC_ADMA=m
CONFIG_SCSI_SATA_QSTOR=m
CONFIG_SCSI_SATA_PROMISE=m
CONFIG_SCSI_SATA_SX4=m
CONFIG_SCSI_SATA_SIL=m
CONFIG_SCSI_SATA_SIL24=m
CONFIG_SCSI_SATA_SIS=m
CONFIG_SCSI_SATA_ULI=m
CONFIG_SCSI_SATA_VIA=m
CONFIG_SCSI_SATA_VITESSE=m
CONFIG_SCSI_SATA_INTEL_COMBINED=y
CONFIG_SCSI_BUSLOGIC=m
# CONFIG_SCSI_OMIT_FLASHPOINT is not set
CONFIG_SCSI_DMX3191D=m
CONFIG_SCSI_DTC3280=m
CONFIG_SCSI_EATA=m
CONFIG_SCSI_EATA_TAGGED_QUEUE=y
CONFIG_SCSI_EATA_LINKED_COMMANDS=y
CONFIG_SCSI_EATA_MAX_TAGS=16
CONFIG_SCSI_FUTURE_DOMAIN=m
CONFIG_SCSI_GDTH=m
# CONFIG_SCSI_GENERIC_NCR5380 is not set
# CONFIG_SCSI_GENERIC_NCR5380_MMIO is not set
CONFIG_SCSI_IPS=m
CONFIG_SCSI_INITIO=m
CONFIG_SCSI_INIA100=m
CONFIG_SCSI_PPA=m
CONFIG_SCSI_IMM=m
# CONFIG_SCSI_IZIP_EPP16 is not set
# CONFIG_SCSI_IZIP_SLOW_CTR is not set
CONFIG_SCSI_NCR53C406A=m
CONFIG_SCSI_SYM53C8XX_2=m
CONFIG_SCSI_SYM53C8XX_DMA_ADDRESSING_MODE=1
CONFIG_SCSI_SYM53C8XX_DEFAULT_TAGS=16
CONFIG_SCSI_SYM53C8XX_MAX_TAGS=64
# CONFIG_SCSI_SYM53C8XX_IOMAPPED is not set
CONFIG_SCSI_IPR=m
# CONFIG_SCSI_IPR_TRACE is not set
# CONFIG_SCSI_IPR_DUMP is not set
CONFIG_SCSI_PAS16=m
CONFIG_SCSI_PSI240I=m
CONFIG_SCSI_QLOGIC_FAS=m
CONFIG_SCSI_QLOGIC_FC=m
# CONFIG_SCSI_QLOGIC_FC_FIRMWARE is not set
CONFIG_SCSI_QLOGIC_1280=m
CONFIG_SCSI_QLA2XXX=y
CONFIG_SCSI_QLA21XX=m
CONFIG_SCSI_QLA22XX=m
CONFIG_SCSI_QLA2300=m
CONFIG_SCSI_QLA2322=m
CONFIG_SCSI_QLA6312=m
CONFIG_SCSI_QLA24XX=m
CONFIG_SCSI_LPFC=m
CONFIG_SCSI_SIM710=m
CONFIG_SCSI_SYM53C416=m
CONFIG_SCSI_DC395x=m
CONFIG_SCSI_DC390T=m
CONFIG_SCSI_T128=m
CONFIG_SCSI_U14_34F=m
CONFIG_SCSI_U14_34F_TAGGED_QUEUE=y
CONFIG_SCSI_U14_34F_LINKED_COMMANDS=y
CONFIG_SCSI_U14_34F_MAX_TAGS=8
CONFIG_SCSI_ULTRASTOR=m
CONFIG_SCSI_NSP32=m
# CONFIG_SCSI_DEBUG is not set
# PCMCIA SCSI adapter support
CONFIG_PCMCIA_NINJA_SCSI=m
# Old CD-ROM drivers (not SCSI, not IDE)
# CONFIG_CD_NO_IDESCSI is not set
CONFIG_I2O_SCSI=m
# NOTE: USB_STORAGE enables SCSI, and 'SCSI disk support'
***************************************************
Je me demande si ce ne serait pas la ligne suivante qui serait à l'origine du problème :
# CONFIG_SCSI_MULTI_LUN is not set
(J'ai lu sur un forum que quelqu'un aurait résolu son pb en mettant l'option max_scsi_luns dans sont lilo.conf).

Confirmes-me tu, sinon vois-tu où pourrait ce situer le problème ?

J'espère être proche de la solution.